JP5874425B2 - Wavelength conversion element and method for manufacturing the same, light emitting device and method for manufacturing the same - Google Patents

Description

  The present invention relates to a light emitting device having a light emitting element and a wavelength conversion unit that converts the wavelength of light emitted from the light emitting element.

  In recent years, a phosphor such as a YAG phosphor is disposed in the vicinity of a gallium nitride (GaN) -based blue LED (Light Emitting Diode) chip, and the blue light emitted from the blue LED chip and the phosphor are blue light. In general, a technique for obtaining a white LED by mixing with yellow light emitted by secondary light emission in response to the light is widely used.

  In such a white LED, a method of sealing an LED chip or a mounting portion using a transparent resin in which a phosphor is dispersed is generally used. However, since the specific gravity of the phosphor is larger than that of the transparent resin, the phosphor settles before the resin is cured, which causes chromaticity variations during light emission.

  Accordingly, various methods for preventing the occurrence of chromaticity variation by suppressing the sedimentation of the phosphor have been proposed. For example, Patent Document 1 encapsulates a silicone resin having a viscosity of 100 to 10,000 mPa · s when the resin is cured. It is described that the use of the phosphor as a body suppresses sedimentation and segregation of the phosphor.

  In Patent Document 2, an LED element is disposed between an upper end opening and a lower end opening of a cylindrical container, and the upper end opening to the lower end opening are filled with a translucent resin. A chip component type LED in which an inner wall surface of a container is formed so as to be reflected toward the opening side is disclosed.

  Further, Patent Document 3 discloses a light emitting device in which a liquid translucent sealing material is added with a lipophilic compound obtained by adding an organic cation to a layered compound mainly composed of clay mineral as an anti-settling agent for a phosphor, and The manufacturing method is disclosed.

JP 2002-314142 A JP 2002-185046 A JP 2004-153109 A

  However, in Patent Document 1, since the LED chip is sealed with a silicone resin, deterioration such as coloring of the sealing material easily proceeds due to light emission from the LED chip, heat generation of the LED chip and the phosphor, and the like. It was difficult to obtain durability sufficient to withstand the use of In addition, the configuration of Patent Document 2 has a problem in that the configuration of the LED is complicated, leading to an increase in cost. Furthermore, in Patent Documents 2 and 3, resin materials such as epoxy resin, silicone resin, and polyimide resin are listed as specific examples of the light-transmitting sealing material. Was not enough.

  Therefore, it is conceivable to improve the heat resistance and light resistance of the LED chip by sealing the LED chip using a sealing material that becomes ceramic after heating. In this case, when the layered compound described in Patent Document 3 is added as a phosphor sedimentation inhibitor, the dispersion state of the phosphor is stabilized, and the occurrence of chromaticity variation can be reduced. However, it is clear that the phosphor and translucent ceramic material react with each other in the solution, resulting in a partial increase in viscosity, which makes it impossible to solidify and apply, that is, a problem of shortening the pot life. became.

  Thus, in the configuration of one liquid, there is a problem that the pot life of the coating liquid itself is shortened, but by sequentially applying the first liquid containing the phosphor and the second liquid containing the translucent ceramic material. The pot life problem is reduced.

  However, when the second liquid is applied after the first liquid is applied, there arises a problem that the adhesion of the film is poor and peels off from the substrate, and a new problem that the film itself is cracked even if the adhesion of the film is good.

In the case of manufacturing a light emitting device by applying a ceramic precursor liquid containing a translucent ceramic material after applying a phosphor dispersion liquid containing a phosphor, the film has good adhesion and cracks in the film. An object of the present invention is to provide a light-emitting device that is difficult to enter. Further, a method of manufacturing the light emitting device, also aims to provide a wavelength conversion element and a manufacturing how used in the light-emitting device.

  In order to achieve the above object, the present invention provides a step of coating a phosphor dispersion containing a phosphor, swellable particles, and a first solvent on a light emitting element to form a film, and a translucent ceramic thereon. And a step of applying a material and a ceramic precursor solution containing a second solvent, and heating the phosphor. The phosphor has a particle size of 5 μm or more when the integrated value of the relative particle amount in terms of volume is 10%. And the particle diameter is 60 μm or less when the integrated value of the relative particle amount in volume conversion is 90%.

  In the above method for manufacturing a light emitting device, the swellable particles are preferably swellable clay minerals.

  In the above method for manufacturing a light-emitting device, the translucent ceramic material is preferably an organometallic compound.

  In the above method for manufacturing a light emitting device, the translucent ceramic material is preferably polysiloxane.

  In the method for manufacturing the light emitting device, the first solvent is preferably an alcohol.

  In the above method for producing a light emitting device, the phosphor dispersion preferably has a viscosity of 80 to 1000 mPa · s.

  In the above method for manufacturing a light-emitting device, it is preferable to apply and heat a silicone sealant after the heating.

  The light-emitting device of the present invention is manufactured by any one of the above-described methods for manufacturing a light-emitting device.

  The present invention also includes a step of applying a phosphor dispersion liquid containing phosphor, swellable particles, and a first solvent on at least one surface of a translucent substrate to form a film, and a translucent ceramic material thereon, And a step of applying and heating a ceramic precursor liquid containing a second solvent, and the phosphor has a particle diameter of 5 μm or more when the integrated value of the relative particle amount in terms of volume is 10%, and The method for producing a wavelength conversion element is characterized in that the particle diameter is 60 μm or less when the integrated value of relative particle amounts in terms of volume is 90%.

  In the above method for producing a wavelength conversion element, the swellable particles are preferably swellable clay minerals.

  In the method for manufacturing a wavelength conversion element, the translucent ceramic material is preferably an organometallic compound.

  In the above method for manufacturing a wavelength conversion element, the translucent ceramic material is preferably polysiloxane.

  In the method for manufacturing a wavelength conversion element, the first solvent is preferably alcohol.

  Moreover, in the manufacturing method of said wavelength conversion element, it is preferable that the viscosity of the said phosphor dispersion liquid is 80-1000 mPa * s.

  In the method for manufacturing a wavelength conversion element, it is preferable that a silicone sealant is applied and heated after the heating.

  Moreover, the wavelength conversion element of this invention is manufactured by said manufacturing method of a wavelength conversion element.

  Moreover, the manufacturing method of the light-emitting device of this invention adds the process of installing a wavelength conversion element in the light emission surface side of a light-emitting element in the manufacturing method of said wavelength conversion element.

  According to the present invention, by applying a phosphor dispersion liquid and then applying a ceramic precursor liquid to produce a light emitting device, it has excellent heat resistance and light resistance, suppresses chromaticity variation, and reduces the pot life of the coating liquid itself. Can be long. In addition, by using a phosphor having an appropriate particle size distribution, the adhesion of the film can be improved and cracks can be prevented from entering the film.

It is a schematic sectional drawing of the light-emitting device of 1st Embodiment of this invention. It is a schematic diagram for demonstrating schematically the coating device using a spray coat method, and a manufacturing method. It is a schematic sectional drawing of the light-emitting device of 2nd Embodiment of this invention. It is a schematic sectional drawing of the light-emitting device of 3rd Embodiment of this invention. It is a figure which shows the particle size distribution in a Example and a comparative example, evaluation of a crack, and evaluation of film peeling.

  Hereinafter, embodiments of a wavelength conversion element and a light emitting device including the same according to the present invention will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view of a light emitting device according to a first embodiment of the present invention. As shown in FIG. 1, in the light emitting device 100, a metal part 2 is provided at the bottom of an LED substrate 1 having a concave cross section, and an LED element 3 is disposed on the metal part 2 as a light emitting element. The LED element 3 is provided with a protruding electrode 4 on a surface facing the metal part 2, and the metal part 2 and the LED element 3 are connected via the protruding electrode 4 (flip chip type).

  In the present embodiment, a blue LED element is used as the LED element 3. The blue LED element is formed, for example, by laminating an n-GaN-based cladding layer, an InGaN light-emitting layer, a p-GaN-based cladding layer, and a transparent electrode on a sapphire substrate.

  Moreover, the wavelength conversion part 6 is provided in the recessed part of the LED board 1 so that the LED element 3 may be covered. The wavelength conversion unit 6 includes a wavelength conversion layer 7 that covers the LED element 3 and a ceramic layer 8 that is formed on the wavelength conversion layer 7. The wavelength conversion layer 7 is a part that converts light having a predetermined wavelength emitted from the LED element 3 into light having a different wavelength, and is excited by the wavelength from the LED element 3 to emit fluorescence having a wavelength different from the excitation wavelength. Contains the body. The ceramic layer 8 is a layer for sealing and protecting the wavelength conversion layer 7, and has translucency that transmits at least the light of the LED element 3 and the fluorescence of the wavelength conversion layer 7.

  Next, the configuration and formation method of the wavelength conversion unit 6 (the wavelength conversion layer 7 and the ceramic layer 8) and the manufacturing method of the light emitting device 100 will be described in detail. The wavelength conversion layer 7 is a layer obtained by applying a mixed liquid (hereinafter, referred to as a phosphor dispersion liquid) containing at least a phosphor, swellable particles, and a solvent (first solvent) and heating (drying). . The phosphor dispersion liquid may contain inorganic particles (inorganic fine particles) and the like.

The ceramic layer 8 is a transparent ceramic layer (glass body) obtained by applying a mixed liquid (hereinafter referred to as a ceramic precursor liquid) containing at least a translucent ceramic material and a solvent and heating (firing). The ceramic precursor liquid may contain swellable particles, water, inorganic particles, and the like.
(Phosphor)

  The phosphor is excited by the wavelength of the light emitted from the LED element 3 (excitation wavelength) and emits fluorescence having a wavelength different from the excitation wavelength. In this embodiment, a YAG (yttrium, aluminum, garnet) phosphor that converts blue light (wavelength 420 nm to 485 nm) emitted from the blue LED element into yellow light (wavelength 550 nm to 650 nm) is used.

  Such phosphors use oxides of Y, Gd, Ce, Sm, Al, La, and Ga, or compounds that easily become oxides at high temperatures, and are mixed well in a stoichiometric ratio. A mixed raw material is obtained. Alternatively, a coprecipitated oxide obtained by calcining a solution obtained by coprecipitation of a solution obtained by dissolving a rare earth element of Y, Gd, Ce, or Sm in an acid with a stoichiometric ratio with oxalic acid, and aluminum oxide or gallium oxide. Mix to obtain a mixed raw material. Then, an appropriate amount of fluoride such as ammonium fluoride is mixed with the obtained mixed raw material as a flux and pressed to obtain a molded body. The obtained molded body is packed in a crucible and fired in air at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours to obtain a sintered body having the phosphor emission characteristics. The phosphor is classified by particle size through a sieve. Then, the classified phosphors are appropriately mixed to obtain a phosphor having a desired particle size distribution.

In this embodiment, the YAG phosphor is used. However, the type of the phosphor is not limited to this. For example, other phosphors such as non-garnet phosphors containing no Ce are used. You can also.
(Swellable particles)

  As the swellable particles, fluoride particles such as magnesium fluoride, aluminum fluoride, and calcium fluoride, layered silicate minerals, imogolite, and allophane can be used. As the layered silicate mineral, a swellable clay mineral having a structure such as a mica structure, a kaolinite structure, or a smectite structure is preferable, and a smectite structure rich in swelling properties is more preferable. Since the layered silicate mineral has a card house structure in the mixed solution, it has an effect of greatly increasing the viscosity of the mixed solution in a small amount. Further, since the layered silicate mineral has a flat plate shape, there is an effect of improving the film strength of the wavelength conversion layer 7.

  The mineral here is a solid substance having a certain chemical composition and crystal structure, which is a natural or synthetic inorganic substance. Such layered silicate minerals include natural or synthetic hectrite, saponite, stevensite, hydelite, montmorillonite, nontrinite, bentonite, and other smectite clay minerals; Examples thereof include swellable mica genus clay minerals such as silicic fluorine mica, Na-type fluorine teniolite, Li-type fluorine teniolite, vermiculite and kaolinite, and mixtures thereof.

  In addition, when the content of the swellable particles in the mixed solution is less than 0.1% by weight, the ratio of solid components such as phosphors, fine particles, and metal alkoxide in the mixed solution increases, and the dispersibility thereof deteriorates. On the other hand, when the content of the swellable particles exceeds 60% by weight, the scattering of excitation light by the swellable particles is often generated, the emission luminance of the wavelength conversion layer 7 is lowered, and the translucency of the ceramic layer 8 is lowered. Therefore, the content of the swellable particles in the mixed solution is preferably 0.1% by weight to 60% by weight, and more preferably 0.5% by weight to 30% by weight.

The swelling particles have a thickening effect, but if the ratio in the wavelength conversion layer 7 or the ceramic layer 8 is high, the viscosity of the liquid mixture does not increase. The viscosity of the liquid mixture is not limited to other solvents, phosphors, etc. Determined by the ratio with the ingredients. In addition, in consideration of compatibility with the solvent, the surface of the swellable particles modified with an ammonium salt or the like (surface treatment) can be used as appropriate.
(solvent)

  As the solvent, water, an organic solvent, or a mixed solvent of water and an organic solvent can be used. Water has a role of swelling hydrophilic swellable particles. For example, the addition of water to the fluoride particles increases the viscosity of the liquid mixture, so that sedimentation of the phosphor can be suppressed. In addition, since there exists a possibility that swelling may be inhibited when the impurity is contained in water, it is necessary to use the pure water which does not contain an impurity as the water to add.

  The organic solvent is used for improving the wettability of the mixed solution and adjusting the viscosity. For example, the addition of an organic solvent to the fluoride particles increases the viscosity of the liquid mixture, so that sedimentation of the phosphor can be suppressed. When water is added to the hydrophilic swellable particles to swell, it is preferable to use monohydric alcohols such as methanol, ethanol, propanol, and butanol having excellent compatibility with water as the organic solvent. Further, it may be a dihydric or higher alcohol such as ethylene glycol, propylene glycol, diethylene glycol, glycerin, 1,3-butanediol, or 1,4-butanediol. Moreover, you may combine 2 or more types of alcohol.

On the other hand, when lipophilic swellable particles are used, water does not act on the swelling of the swellable particles, but the viscosity increases by adding water, so an organic solvent having excellent compatibility with water should be used. preferable. Moreover, by using an organic solvent having a high boiling point such as ethylene glycol or propylene glycol, the pot life of the mixed solution is not shortened, and the nozzle is prevented from being clogged at the time of spray coating, and the handling property is excellent.
(Inorganic particles)

  The inorganic particles have a filling effect that fills a gap generated at the interface between the phosphor and the swellable particles, and a thickening effect that increases the viscosity of the mixed solution before heating. Examples of usable inorganic particles include fine oxide particles such as silicon oxide, titanium oxide, zinc oxide, aluminum oxide, and zirconium oxide. In consideration of compatibility with ceramic materials and solvents, inorganic particles whose surfaces are treated with a silane coupling agent or a titanium coupling agent can be used as appropriate.

  In addition, when the content of the inorganic particles in the wavelength conversion layer 7 is less than 0.5% by weight, the ratio of solid components such as phosphors in the phosphor dispersion liquid increases, and the dispersibility of the phosphors deteriorates. Handling becomes difficult, and it becomes difficult to apply with uniform chromaticity. On the other hand, if the content of the inorganic particles exceeds 70% by weight, the scattering of excitation light by the inorganic particles occurs frequently, and the light emission luminance of the wavelength conversion layer 7 decreases. Therefore, the content of inorganic particles in the phosphor dispersion is preferably 0.5% by weight or more and 70% by weight or less, more preferably 0.5% by weight or more and 65% by weight or less, and more preferably 1% by weight or more and 60% by weight. The following is more preferable.

  The inorganic particles have a thickening effect, but if the ratio in the wavelength conversion layer 7 is high, the viscosity of the liquid mixture does not increase. The viscosity of the liquid mixture is a ratio with other components such as a solvent and a phosphor. Determined.

The particle size distribution of the inorganic particles is not particularly limited, and may be distributed over a wide range or may be distributed over a relatively narrow range. As the particle size of the inorganic particles, the central particle size of the primary particle size is 0.001 μm or more and 50 μm or less, preferably smaller than the phosphor, and smaller than the thickness of the wavelength conversion layer 7 after heating. The average particle diameter of the inorganic particles can be measured, for example, by a Coulter counter method.
(Translucent ceramic material)

  The translucent ceramic material is a ceramic precursor, and an inorganic or organic metal compound can be used. Examples of the metal compound include metal alkoxides, metal acetylacetonates, metal carboxylates, metal nitrates, metal oxides, and the like, and metal alkoxides that are easily gelled by hydrolysis and polymerization reaction are preferable.

The metal alkoxide may be a single molecule such as tetraethoxysilane, or may be a polysiloxane in which an organic siloxane compound is linked in a chain or a ring, but a polysiloxane that increases the viscosity of the mixed solution is preferable. In addition, there is no restriction | limiting in the kind of metal if a translucent glass body can be formed, but it is preferable to contain a silicon | silicone from a viewpoint of the stability of the glass body formed and the ease of manufacture. Moreover, you may contain multiple types of metal.
(Procedure for adjusting phosphor dispersion)

  As a procedure for preparing the phosphor dispersion liquid, a phosphor, swellable particles, a solvent and the like may be simply mixed. If the viscosity of the phosphor dispersion liquid is too high, the nozzles are likely to be clogged during spray coating, while if the clay is too low, the phosphor tends to settle. Therefore, the viscosity of the phosphor dispersion liquid is usually 10 to 1000 mPa · s, preferably 80 to 1000 mPa · s, and more preferably 200 to 450 mPa · s.

Further, when the phosphor dispersion liquid contains a translucent ceramic material, the phosphor and the translucent ceramic material react with each other to increase the viscosity partially, making it impossible to singulate and apply, that is, pot life. The problem of shortening occurs. Therefore, it is preferable that the phosphor dispersion liquid containing phosphor, swellable particles, solvent and the like does not contain a translucent ceramic material.
(Ceramic precursor liquid adjustment procedure)

  As a procedure for preparing the ceramic precursor liquid, swellable particles, water, and inorganic particles may be mixed in a solution in which a translucent ceramic material is dispersed in a solvent as necessary. By adding swellable particles to the ceramic precursor liquid, a translucent ceramic layer that is less prone to cracking even when thickly applied can be formed.

As the ceramic precursor liquid, the sol-like precursor solution may be heated to a gel state, and further fired to form a transparent ceramic layer by a so-called sol-gel method, or gelled by firing. Alternatively, the transparent ceramic layer may be directly formed. When using the sol-gel method, it is preferable to appropriately mix, for example, a metal alkoxide, water for hydrolysis, a solvent, a catalyst, and the like. As the catalyst, hydrochloric acid, sulfuric acid, nitric acid, acetic acid, hydrofluoric acid, ammonia and the like can be used. When tetraethoxysilane is used as the metal alkoxide, it is preferable to use 138 parts by mass of ethyl alcohol and 52 parts by mass of pure water with respect to 100 parts by mass of tetraethoxysilane. In this case, the heating temperature of the gel is preferably 120 to 250 ° C., and 120 to 200 ° C. is preferable from the viewpoint of further suppressing the deterioration of the LED element 3. Moreover, when using polysiloxane as a metal alkoxide, 120-500 degreeC is preferable for the heating temperature after application | coating, and 120-350 degreeC is preferable from a viewpoint which suppresses deterioration of the LED element 3 more.
(Method for manufacturing light emitting device)

  A predetermined amount of the phosphor dispersion liquid obtained as described above is sprayed on the LED substrate 1 on which the LED elements 3 are mounted by a spray coating method. In FIG. 2, the schematic diagram for demonstrating schematically the coating device using a spray coat method, and a manufacturing method is shown. The coating device 10 mainly includes a movable table 20 that can move up and down, left and right, and back and forth, and a spray device 30 that can spray the phosphor dispersion liquid.

  The spray device 30 is disposed above the movable table 20. The spray device 30 has a nozzle 32 into which air is sent, and an air compressor (not shown) for sending air is connected to the nozzle 32. The hole diameter at the tip of the nozzle 32 is 20 μm to 2 mm, preferably 0.1 to 0.3 mm. The nozzle 32 can move up and down, left and right, and back and forth, like the moving table 20.

  For example, the spray gun W-101-142BPG manufactured by Anest Iwata is used as the nozzle 32, and the OFP-071C manufactured by Anest Iwata is used as the compressor. The angle of the nozzle 32 can be adjusted, and the nozzle 32 can be tilted with respect to the movable table 20 (or the LED substrate 1 installed on the moving table 20). The angle of the nozzle 32 with respect to the injection target (LED substrate 1) is preferably in the range of 0 to 60 ° when the vertical direction from the injection target is 0 °.

  A tank 36 is connected to the nozzle 32 via a connecting pipe 34. A phosphor dispersion liquid 40 is stored in the tank 36. The tank 36 contains a stirring bar, and the phosphor dispersion liquid 40 is constantly stirred. If the phosphor dispersion liquid 40 is agitated, sedimentation of the phosphor having a large specific gravity can be suppressed, and the state in which the phosphor is dispersed in the phosphor dispersion liquid 40 can be maintained. For example, Anest Iwata PC-51 is used as the tank.

  When the phosphor dispersion liquid 40 is actually applied, a plurality of LED substrates 1 (on which the LED elements 3 are mounted in advance) are installed on the moving table 20, and the positional relationship between the LED substrate 1 and the nozzle 32 of the spray device 30. Is adjusted (position adjustment step).

  Specifically, the LED substrate 1 is installed on the moving table 20, and the LED substrate 1 and the tip end portion of the nozzle 32 are arranged to face each other. Although the phosphor dispersion liquid 40 can be uniformly applied as the distance between the LED substrate 1 and the nozzle 32 increases, the film strength tends to decrease. It is suitable to keep the distance in the range of 3 to 30 cm.

  Thereafter, while the LED substrate 1 and the nozzle 32 are moved relative to each other, the phosphor dispersion liquid 40 is sprayed from the nozzle 32 to apply the phosphor dispersion liquid 40 to the LED substrate 1 (spraying / coating process). Specifically, on the other hand, the moving base 20 and the nozzle 32 are moved to move the LED substrate 1 and the nozzle 32 back and forth and right and left. Either one of the moving table 20 and the nozzle 32 may be fixed, and the other may be moved back and forth and left and right. A method of applying a plurality of LED elements 3 in a direction orthogonal to the moving direction of the moving table 20 and moving the nozzle 32 in a direction orthogonal to the moving direction of the moving table 20 is also preferably used.

  On the other hand, air is sent to the nozzle 32 and the phosphor dispersion liquid 40 is sprayed from the tip of the nozzle 32 toward the LED substrate 1. The distance between the LED substrate 1 and the nozzle 32 can be adjusted in the above range in consideration of the pressure of the air compressor. For example, the pressure of the compressor is adjusted so that the pressure (spray pressure) at the inlet (tip) of the nozzle 32 is 0.14 MPa. With the above operation, the phosphor dispersion liquid 40 can be applied onto the LED element 3.

  Instead of using the coating apparatus 10, the phosphor dispersion liquid and the ceramic precursor liquid may be applied (dropped or discharged) using a dispenser or an inkjet apparatus. In the case of using a dispenser, a nozzle that can control the dropping amount of the coating liquid and that does not cause nozzle clogging such as a phosphor is used. For example, a non-contact jet dispenser manufactured by Musashi Engineering Co., Ltd. or its dispenser can be used. Even when an ink jet apparatus is used, a nozzle that can control the discharge amount of the coating liquid and does not cause clogging of nozzles such as phosphors is used. For example, an ink jet apparatus manufactured by Konica Minolta IJ can be used.

  By heating (drying) the phosphor dispersion liquid thus applied, the wavelength conversion layer 7 having a uniform thickness (uniform phosphor distribution) is formed on the LED element 3. Next, a predetermined amount of the ceramic precursor liquid is sprayed on the wavelength conversion layer 7 by a spray coating method. The coating apparatus 10 can also be used here. Part of the applied ceramic precursor liquid penetrates into the gaps between the phosphor and the swellable particles. The ceramic layer 8 is formed by heating (baking) this.

  Here, since the ceramic precursor liquid that has penetrated into the wavelength conversion layer 7 is changed to ceramic, the ceramic acts as a binder for the phosphor, the swellable particles, and the LED element 3. In addition, since the ceramic precursor liquid has an appropriate viscosity, the ceramic layer 8 is clearly formed on the wavelength conversion layer 7 and has a function of sealing the wavelength conversion layer 7.

  If there are many phosphors having a small particle diameter in the phosphor dispersion liquid, the ceramic precursor liquid is impregnated or adsorbed on these small diameter particles having a large specific surface area, and the ceramic precursor liquid does not reach the LED element 3. Thereby, the adhesion of the film to the LED element 3 after firing is lowered, and film peeling is likely to occur.

  On the other hand, if a large number of phosphors having a large particle diameter are present, the distance between the phosphor particles becomes long, so that the thickness of the ceramic precursor liquid filled between the phosphor particles increases, so that the ceramic layer 8 cracks due to shrinkage during firing. Is likely to occur. Therefore, it is necessary to use a phosphor having an appropriate particle size distribution in order to prevent film peeling and to prevent cracks during sintering. This will be described in detail later.

  Moreover, when the thickness of the formed wavelength conversion part 7 is less than 5 micrometers, wavelength conversion efficiency falls and sufficient fluorescence is not obtained, and when the thickness of the wavelength conversion layer 7 exceeds 500 micrometers, film | membrane intensity | strength falls. Cracks and the like are likely to occur. Therefore, the thickness of the wavelength conversion layer 7 is preferably 5 μm or more and 500 μm or less.

  FIG. 3 is a schematic cross-sectional view of the light emitting device according to the second embodiment of the present invention. As shown in FIG. 3, in the light emitting device 101, a metal part 2 is provided on a flat LED substrate 1, and the LED element 3 is disposed on the metal part 2 as a light emitting element. The LED element 3 is provided with a protruding electrode 4 on a surface facing the metal part 2, and the metal part 2 and the LED element 3 are connected via the protruding electrode 4 (flip chip type).

  A wavelength conversion element 9 is provided on the upper surface of the LED element 3. The wavelength conversion element 9 includes a glass substrate 5 and a wavelength conversion unit 6 formed on the upper surface of the glass substrate 5. The shape of the glass substrate 5 is not particularly limited, and a flat plate shape, a lens shape, or the like can be adopted. The wavelength conversion unit 6 may be formed on the lower surface of the glass substrate 5. The wavelength conversion unit 6 includes a wavelength conversion layer 7 formed on the glass substrate 5 and a ceramic layer 8 formed on the wavelength conversion layer 7.

  As a manufacturing method of the light emitting device 101, a predetermined amount of the phosphor dispersion liquid is applied to one side of the glass substrate 5, and heated to form the wavelength conversion layer 7 having a predetermined thickness. Next, a predetermined amount of the ceramic precursor liquid is applied to the upper surface of the wavelength conversion layer 7. Part of the applied ceramic precursor liquid penetrates into the gaps between the phosphor particles and the swellable particles. The ceramic layer 8 is formed by baking the glass substrate 5 to which the ceramic precursor liquid is applied.

  The method for applying the phosphor dispersion liquid and the ceramic precursor liquid is not particularly limited, and various conventionally known methods such as a bar coating method, a spin coating method, and a spray coating method can be used.

  And the light-emitting device 101 can be manufactured by cut | disconnecting the glass substrate 5 in which the wavelength conversion part 6 was formed to predetermined magnitude | size (for example, 2x2 mm), and arrange | positioning on the LED element 3. FIG.

  In addition, although the glass substrate 5 is used in the said embodiment, if it is a board | substrate which consists of not only a glass substrate but a translucent inorganic material, for example, crystal substrates, such as a single crystal sapphire, and a ceramic substrate will be used. Also good.

  FIG. 4 is a schematic cross-sectional view of a light emitting device according to a third embodiment of the present invention. As shown in FIG. 4, in the light emitting device 102, the metal part 2 is provided at the bottom of the LED substrate 1 having a concave cross section, the LED element 3 is disposed on the metal part 2, and a lid is provided on the concave part of the LED substrate 1. Thus, a wavelength conversion element 9 is provided. Since the configuration of other parts including the wavelength conversion element 9 is the same as that of the second embodiment, the description thereof is omitted.

  In the light emitting device 102 of the present embodiment, the LED element 3 is disposed in the concave portion of the LED substrate 1, and the wavelength conversion element 9 used in the second embodiment is bonded to the upper end of the side wall of the LED substrate 1 so as to cover the concave portion. Can be manufactured.

  In the light emitting device 102 of the present embodiment, light emitted from the side surface of the LED element 3 is also efficiently converted into fluorescence as compared to the second embodiment.

  The shape and size of the concave portion of the LED substrate 1 can be appropriately designed according to the specification of the light emitting device 102. For example, the side surface of the recess may be tapered. In addition, a configuration in which the light emission efficiency of the light emitting device 102 is increased by using the inner surface of the recess as a reflection surface may be employed.

  In addition, the present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and can be obtained by appropriately combining technical means disclosed in different embodiments. Embodiments are also included in the technical scope of the present invention. In each of the above embodiments, a light emitting device that emits white light by using a blue LED and a phosphor together has been described as an example. However, the same applies to a case where a green LED or a red LED and a phosphor are used in combination. Of course you can. Furthermore, not only one type of phosphor, but also three types of phosphors that absorb ultraviolet light and emit red, green, and blue light, respectively, and red and green light that absorb blue light, respectively. You may use together two types of fluorescent substance to radiate | emit. In addition, a translucent ceramic layer such as the above-described ceramic layer 8 may be formed on the surface of the glass substrate 5 or the LED element 3 before applying the phosphor dispersion liquid.

Hereinafter, the light emitting device of the present invention will be described more specifically with reference to Examples and Comparative Examples. Examples 1 to 3 are examples of the light emitting device 100 of the first embodiment, and Comparative Examples 1 to 5 are examples of a light emitting device having the same shape as the light emitting device 100 of the first embodiment. In addition, although the example of 2nd and 3rd Embodiment was abbreviate | omitted, the result similar to Examples 1-3 was obtained.
(Phosphor preparation example)

Phosphor used in the Examples and Comparative Examples, mixing the phosphor _{material, Y 2 O 3 7.41g, Gd} 2 O 3 4.01g, CeO 2 0.63g, the Al ₂ O 3 7.77 g fully Then, an aluminum crucible mixed with an appropriate amount of ammonium fluoride as a flux is filled in an aluminum crucible and baked at a temperature range of 1350 to 1450 ° C. for 2 to 5 hours in a reducing atmosphere in which hydrogen-containing nitrogen gas is passed. In this way, a fired product ((Y _0.72 Gd _0.24 ) ₃ Al ₅ O ₁₂ : Ce _0.04 ) was obtained.

  The obtained fired product was pulverized, washed, separated, dried, and classified to obtain yellow phosphor particles. When the emission wavelength of excitation light with a wavelength of 465 nm was measured, it had a peak wavelength at a wavelength of approximately 570 nm.

  The classification of the phosphors is performed by sieving, so that the particle size when the integrated value of the relative particle amount in terms of volume is 50% is 3, 5, 10, 15, 20, 25, 30, 35, 40, respectively. , 45, 50, 55, 60, 65, 70, 75, 80, 85, 90 μm. And the fluorescent substance AH which has the conversion particle diameter shown in FIG. 5 was obtained by mixing each classified fluorescent substance suitably. In FIG. 5, D10 is the particle size when the integrated value of the relative particle amount in terms of volume is 10%, D50 is the particle size when the integrated value of the relative particle amount in terms of volume is 50%, and D90 is in terms of volume. Represents the particle diameter when the integrated value of the relative particle amounts is 90%.

The particle size distribution of the phosphor was measured with respect to the phosphor dispersion using a laser diffraction particle size distribution analyzer SALD-7000 (Shimadzu Corporation). In this measuring apparatus, the particle size distribution in terms of number and the particle size distribution in terms of volume can be obtained. Here, the particle size distribution in terms of volume was used.
(Preparation of phosphor dispersions of Examples 1 to 3 and Comparative Examples 1 to 5)

In Examples 1 to 3, phosphor dispersions were prepared as follows using phosphors D to F and Comparative Examples 1 to 5 using phosphors A to C, G, and H, respectively. For 100 parts by weight of the phosphor, 90 parts by weight of butanediol and 50 parts by weight of isopropyl alcohol as a solvent, 3 parts by weight of Bengel (natural bentonite sold by Hojun Co.) as a swellable clay mineral, and RX300 (sold by Nippon Aerosil Co., Ltd.) as inorganic fine particles (Silica) 3 parts by weight was added and mixed, and this was dispersed using a TK homomixer (manufactured by Primix) to obtain a phosphor dispersion. When the viscosity of this fluorescent substance dispersion liquid was measured, all of Examples 1-3 and Comparative Examples 1-5 were 150 mPa * s. Viscosity measurement was performed using a vibration viscometer VM-10A (manufactured by Seconic Corp.) and reading the value one minute after the vibrator was immersed in the liquid.
(Preparation of ceramic precursor solutions of Examples 1 to 3 and Comparative Examples 1 to 5)

A ceramic precursor liquid was obtained by mixing 15 parts by weight of polysiloxane and 85 parts by weight of isopropyl alcohol.
(Production of light emitting device)

The phosphor dispersion liquid is sprayed onto the concave portion of the LED substrate 1 and the surface of the LED element 3 at a spray pressure of 0.2 MPa and a moving speed of 100 mm / s using the coating apparatus 10 and heated at 150 ° C. for 1 hour. Then, the wavelength conversion layer 7 was produced by drying. Next, the ceramic precursor liquid is sprayed onto the wavelength conversion layer 7 using the coating apparatus 10 at a spray pressure of 0.1 MPa and a moving speed of the moving table 20 of 100 mm / s, and heated at 150 ° C. for 1 hour to be fired. As a result, the phosphor of the wavelength conversion layer 7 was fixed, and the ceramic layer 8 was produced, whereby the light emitting device 100 was obtained.
(Evaluation, examination)

  About the sample of each Example and the comparative example, evaluation of a crack and evaluation of film peeling were performed. FIG. 5 shows the result. For the evaluation of the crack, the wavelength conversion part of the light emitting device is observed with a microscope, the crack is not seen and it can be used practically, `` ○ '', the slightly cracked thing that is not practically preferable is `` △ '', clearly The case where cracks could be confirmed and was impractical was designated as “x”.

  For the evaluation of film peeling, the light emitting device was repeatedly dropped on the iron plate from a height of 50 cm, and it was visually confirmed whether or not the wavelength conversion unit 6 was peeled off from the surface of the LED element 3. And, when the wavelength conversion unit 6 is peeled off, the number of drops is 50 or more when it can withstand practical use, “◯”, and the case of 30 to 49 times is not preferable for practical use. Those with 29 times or less were marked as “x” as impractical.

  As a result, as shown in FIG. 5, the light emitting devices of Examples 1 to 3 were able to withstand practical use with good evaluation of cracks and evaluation of film peeling. On the other hand, in Comparative Examples 1 to 3, the evaluation of film peeling is x or Δ, and in Comparative Examples 3 to 5, the evaluation of crack is x or Δ.

  First, in order to consider film peeling, the particle size distributions of Examples 1 to 3 and Comparative Examples 1 to 5 are compared. In Examples 1 to 3 and Comparative Examples 4 and 5 in which the evaluation of film peeling is ○, the particle diameter (D10) when the integrated value of the relative particle amount in terms of volume is 10% is 5 to 15 μm. On the other hand, in Comparative Examples 1 to 3 in which the evaluation of film peeling is x or Δ, D10 is 3 to 4 μm.

  From this, it can be said that the phosphor should have a thickness of 5 μm ≦ D10 in order to have good film adhesion and suppress film peeling. This is because when a large number of small-diameter phosphors are present in the phosphor dispersion liquid, the ceramic precursor liquid is impregnated or adsorbed on these small-diameter particles having a large specific surface area, and the ceramic precursor liquid does not reach the LED element 3. It is considered that the adhesion of the film to the LED element 3 after firing is lowered and film peeling is likely to occur.

  Next, in order to consider cracks, the particle size distributions of Examples 1 to 3 and Comparative Examples 1 to 5 are compared. In Examples 1 to 3 and Comparative Examples 1 and 2 in which the evaluation of the crack is ○, D90 is 40 to 60 μm. On the other hand, in Comparative Examples 3, 4, and 5 where the crack evaluation is x or Δ, D90 is 65 to 80 μm.

  From this, it can be said that D90 ≦ 60 μm is sufficient to prevent cracking during sintering. This is because when a large number of phosphors having a large particle size are present in the phosphor dispersion liquid, the distance between the phosphor particles becomes long, and the thickness of the ceramic precursor liquid filled between the phosphor particles increases, which causes shrinkage during firing. It is considered that cracks are likely to occur in the ceramic layer 8.

  Therefore, it can be said that when the particle size distribution of the phosphor in the phosphor dispersion liquid is 5 μm ≦ D10 and D90 ≦ 60 μm, a light-emitting device is obtained in which film peeling hardly occurs and cracks do not occur during sintering.

  In the light emitting device of the present invention, for the purpose of improving the gas barrier property, improving the physical strength, improving the light extraction efficiency, etc., the ceramic precursor liquid is applied and heated, and then the silicone sealing agent is applied and heated. Thus, a silicone sealing layer may be provided on the ceramic layer 8. As the silicone sealant, a resin having as a skeleton a structure in which silicon atoms having an organic group such as an alkyl group or an aryl group are alternately bonded to oxygen atoms can be used. In addition, you may provide another additive element to this frame | skeleton. For example, a silicone silicone sealing layer can be formed by applying phenyl silicone (Shin-Etsu Chemical Co., Ltd .; KER-6000) on the ceramic layer 8 and heating at 150 ° C. for 1 hour.

1 LED board 3 LED element (light emitting element)
5 Glass substrate (translucent substrate)
6 Wavelength conversion unit 7 Wavelength conversion layer 8 Ceramic layer 9 Wavelength conversion element 100, 101, 102 Light emitting device

Claims (17)

Applying a phosphor dispersion containing a phosphor, swellable particles, and a first solvent on a light emitting element to form a film;
On top of that, a step of applying and heating a translucent ceramic material and a ceramic precursor liquid containing a second solvent,
The phosphor has a particle size of 5 μm or more when the integrated value of relative particle amount in terms of volume is 10%, and a particle size of 60 μm or less when the integrated value of relative particle amount in terms of volume is 90%. A method for manufacturing a light-emitting device.   The method for manufacturing a light emitting device according to claim 1, wherein the swellable particles are swellable clay minerals.   3. The method for manufacturing a light emitting device according to claim 1, wherein the translucent ceramic material is an organometallic compound.   3. The method of manufacturing a light emitting device according to claim 1, wherein the translucent ceramic material is polysiloxane.   The method for manufacturing a light emitting device according to claim 1, wherein the first solvent is an alcohol.   The method for manufacturing a light emitting device according to claim 1, wherein the phosphor dispersion liquid has a viscosity of 80 to 1000 mPa · s.   The method for manufacturing a light-emitting device according to claim 1, wherein after the heating, a silicone sealant is applied and heated.   The light-emitting device manufactured by the manufacturing method of the light-emitting device in any one of Claims 1-7. Applying a phosphor dispersion liquid containing phosphor, swellable particles, and a first solvent to at least one surface of a translucent substrate;
On top of that, a step of applying and heating a translucent ceramic material and a ceramic precursor liquid containing a second solvent,
The phosphor has a particle size of 5 μm or more when the integrated value of relative particle amount in terms of volume is 10%, and a particle size of 60 μm or less when the integrated value of relative particle amount in terms of volume is 90%. A method for producing a wavelength conversion element, wherein   The method for producing a wavelength conversion element according to claim 9, wherein the swellable particles are swellable clay minerals.   The method for manufacturing a wavelength conversion element according to claim 9 or 10, wherein the translucent ceramic material is an organometallic compound.   The method of manufacturing a wavelength conversion element according to claim 9 or 10, wherein the translucent ceramic material is polysiloxane.   The method for manufacturing a wavelength conversion element according to claim 9, wherein the first solvent is alcohol.   The method for producing a wavelength conversion element according to any one of claims 9 to 13, wherein the phosphor dispersion liquid has a viscosity of 80 to 1000 mPa · s.   The method for manufacturing a wavelength conversion element according to claim 9, wherein after the heating, a silicone sealing agent is applied and heated.   The wavelength conversion element manufactured by the manufacturing method of the wavelength conversion element in any one of Claims 9-15. The manufacturing method of the light-emitting device which added the process of installing the said wavelength conversion element in the light emission surface side of a light emitting element to the manufacturing method of the wavelength conversion element in any one of Claims 9-15 .

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