JP2013026590A - Light-emitting device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device manufacturing method which makes it possible to restrict color irregularities depending on view angles and also to reduce material and manufacturing costs.SOLUTION: A light-emitting element is mounted at the bottom of a recessed part of a case. Next, a mask having an opening corresponding to the light-emitting element mounted part is disposed on the top face of the case, and a mixed liquid consisting of phosphor particles dispersed in a volatile solvent is screen-printed to supply the mixed liquid to the periphery of the light-emitting element. After that, the mixed liquid is heated to evaporate the volatile solvent. Since screen printing is used to apply a coating of the mixed liquid to the light-emitting element mounted part, collective application of the mixed liquid is made possible and manufacturing cost is thereby reduced. Furthermore, since the phosphor is closely contacted with the light-emitting element by evaporating the volatile solvent into which phosphor particles have been mixed, a sufficient wavelength conversion rate can be obtained even when the amount of phosphor particles supplied is reduced, which results in reduced material costs.

Description

  The present invention relates to a method of manufacturing a light-emitting device that uses a light-emitting element and a phosphor that emits wavelength-converted light when excited by light emitted from the light-emitting element, and obtains white light using mixed light of the emitted light and wavelength-converted light. It is about.

  A so-called white LED lamp uses an LED chip and phosphor particles that are excited by the light emitted from the LED chip and convert the light emitted from the LED chip into wavelength-converted light having a longer wavelength than the light emitted from the LED chip. Get light. In general, white LED lamps often contain phosphor particles in a sealing material for sealing an LED chip.

  In such an LED lamp, phosphor particles are contained in the encapsulant mainly by one of the following two methods.

  In the first type, as shown in FIG. 1A, phosphor particles 5 are uniformly mixed in an uncured encapsulant 6 containing a thixotropic agent such as aerosil in the recess of case 1. Is supplied and then cured to uniformly disperse the phosphor particles in the sealing material 6 (see, for example, Patent Document 1).

  In the second method, as shown in FIG. 1B, the phosphor particles 5 are uniformly mixed and supplied to the recesses of the case 1 in the uncured sealing material 6 so that the sealing material 6 is uncured. In this state or in a state where the viscosity is lowered during curing, the phosphor particles 5 are allowed to settle around the LED chip 2 and then the sealing material 6 is cured (see, for example, Patent Document 2).

In the first type of method, the emitted light from the LED chip 2 is absorbed to some extent by the sealing material 6 before reaching the phosphor particles 5, so that the phosphor particles 5 with the initial light intensity emitted from the LED chip 2. Can not be excited. Therefore, in order to obtain a sufficient wavelength conversion rate, it is necessary to increase the content of the phosphor particles 5 in the sealing material 6, and the material cost becomes high.
Further, since the optical path length from the LED chip 2 to the outside of the sealing material 6 varies depending on the viewing angle, color unevenness due to the viewing angle occurs due to the different wavelength conversion probabilities in the phosphor particles 5. It was.

On the other hand, in the second type of method, the phosphor particles 5 are arranged in the vicinity of the LED chip 2, so that the absorption of the emitted light from the LED chip 2 by the sealing material 6 is small, and the phosphor particles have high light intensity. 5 is excited. Therefore, even if the content of the phosphor particles 5 in the sealing material 6 is small, a sufficient wavelength conversion rate can be obtained, and the material cost can be reduced.
However, since it is difficult to completely settle the phosphor particles 6, color unevenness due to the viewing angle still occurs. Moreover, since it takes time for the phosphor particles 6 to settle, the manufacturing cost becomes high. Further, when a plurality of types of phosphor particles 6 are used in combination, since the specific gravity and particle size are different between the different phosphor particles 6, the sedimentation speed is also different. For this reason, it is difficult to control the sedimentation mode of the phosphor particles 6, and it is also difficult to control the chromaticity.

  In order to solve the above problems in the method of precipitating the phosphor particles, a mixed liquid is prepared by mixing the phosphor particles in a volatile solvent, and the mixed liquid is dispensed or spray coated around the LED chip mounting portion. A method of arranging phosphor particles by volatilizing a volatile solvent after coating has been proposed (see, for example, Patent Documents 3 to 6).

  According to this method, since the phosphor particles are uniformly applied in contact with the LED chip, the color unevenness can be improved and the settling time of the phosphor can be omitted, so that the manufacturing cost can be reduced.

Japanese National Patent Publication No. 11-500584 JP-A-11-040858 JP 2005-277127 A JP 2003-115614 A JP 2004-088013 A JP 2009-076649 A

  However, in the application by dispensing or spray coating, it is necessary to apply the mixed solution to each LED chip. Therefore, since it takes time to apply the mixed solution, the manufacturing cost is still not sufficiently reduced.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a method for manufacturing a light-emitting device that reduces material costs and manufacturing costs while suppressing color unevenness due to viewing angles. To do.

In order to solve the above problems, the present invention provides a method for manufacturing a light emitting device having the following configuration.
That is, an element mounting step of mounting a light emitting element on the bottom of a recess provided in the case, and a mask arranging step of disposing a mask provided with an opening corresponding to the mounting portion of the light emitting element on the top surface of the case; Using the mask, screen-printing a mixed liquid in which phosphor particles are dispersed in a volatile solvent, and applying the mixed liquid around the light-emitting element mounting portion in the recess; And a solvent volatilizing step for volatilizing the volatile solvent of the mixed liquid by heating.

In the method for manufacturing a light emitting device of the present invention, since the mixed liquid is applied to the mounting portion of the light emitting element using screen printing, it is possible to apply the mixed liquid all at once, and the manufacturing cost is low. In addition, by volatilizing the volatile solvent mixed with the phosphor particles, the phosphor is in close contact with the light-emitting element, so that a sufficient wavelength conversion rate can be obtained even if the amount of phosphor particles supplied is reduced. The material cost will be low.
In general, in screen printing, a printed material can be applied by moving a squeegee while the mask is in close contact with an object to be printed. In the present invention, since the recess is formed in the case, the mask is not in a close contact state as a whole, but since the mask is supported by the top surface of the case, the liquid mixture is applied to the periphery of the light emitting element. be able to.

1A and 1B are cross-sectional views showing a conventional LED lamp, and FIG. 1A is a cross-sectional view showing an LED lamp in which phosphor particles are dispersed in a sealing material. FIG.1 (b) is sectional drawing which shows the LED lamp which made the fluorescent substance settle in a sealing material. 2A to 2D are top views showing the shape of the opening of the mask used in the embodiment of the present invention, and FIG. 2A is a top view showing a single circular opening. FIG. 2B is a top view showing a single quadrangular opening, and FIG. 2C is a top view showing an opening in which a plurality of quadrangles are arranged in a grid pattern. 2 (d) is a top view showing an opening in which a plurality of hexagons are arranged in a honeycomb shape. 3 (a) to 3 (c) are cross-sectional views showing a method for manufacturing an LED lamp according to an embodiment of the present invention, and FIG. 3 (a) is a cross-sectional view showing a case material forming step. (B) is sectional drawing which shows an LED chip mounting process, FIG.3 (c) is sectional drawing which shows a mask arrangement | positioning process. 4 (a) to 4 (d) are cross-sectional views showing a method for manufacturing an LED lamp according to an embodiment of the present invention, and FIG. 4 (a) is a cross-sectional view showing a mixed liquid coating process. (B) is sectional drawing which shows a solvent volatilization process, FIG.4 (c) is sectional drawing which shows a sealing process, FIG.4 (d) is sectional drawing which shows an individualization process.

  First, each component used for the manufacturing method of the LED lamp of embodiment of this invention is demonstrated.

(LED chip)
The LED chip used in the embodiment of the present invention is not particularly limited as long as it is an LED chip that emits violet light (peak wavelength: 380 nm to 450 nm) or blue light (peak wavelength: 450 nm to 495 nm).

  For example, an LED chip using a group III nitride compound semiconductor (Al1-X—YInXGaYN, 0 ≦ X ≦ 1, 0 ≦ Y ≦ 1, 0 ≦ X + Y ≦ 1) can be used.

  An LED chip made of a group III nitride compound semiconductor has a desired structure in which a semiconductor laminate having a buffer layer, an n-type layer, a light emitting layer, and a p-type layer is grown in this order from the growth substrate side on a growth substrate made of sapphire. In order to make contact with the n-type layer in this region, etching is performed from the p-type layer side until the n-type layer is exposed, and a contact electrode is formed on each of the p-type layer and the n-type layer.

  The semiconductor stack may be formed by, for example, metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy (MBE), halide vapor phase epitaxy (Halide VaporPePeH, etc.). Is done.

  As the LED chip used in the embodiment of the present invention, a reflective electrode such as an Ag alloy or Ag / Al is used as a contact electrode with the p-type layer, and the LED chip mainly having a light extraction surface on the growth substrate side ( A so-called flip chip type LED chip) or a transparent conductive oxide such as ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), or ICO (Indium Cerium Oxide) is mainly used as a contact electrode of a p-type layer. An LED chip (so-called face-up type LED chip) having a light extraction surface on the semiconductor laminate side can be mentioned.

  Further, as described above, after a semiconductor laminate is grown on the growth substrate, a conductive substrate made of Si, GaAs, Cu, CuW, or the like is attached to the semiconductor laminate, and then the growth substrate is removed by laser irradiation. A double-sided electrode type LED chip (so-called LLO (Laser Lift Off) type chip) obtained by forming electrodes on each of the n-type layer exposed by removing the back surface of the conductive substrate and the growth substrate can also be used. .

(Case)
The case used in the embodiment of the present invention is not particularly limited as long as a concave portion having an inner side surface and a bottom surface is formed on the top surface which is a surface on the light emission side.

  For example, a resin case molded together with a lead frame can be used. In this case, the resin case may be formed with a recess according to the mold by injection molding using a polyphthalamide resin or liquid crystal polymer resin that is a thermoplastic resin, or an epoxy resin that is a thermosetting resin, or a modified resin. You may form a recessed part according to a metal mold | die by transfer molding using an epoxy resin, a silicone resin, and a modified silicone resin.

  A ceramic case formed by sintering a laminate of green sheets can be used. In this case, the concave portion is formed by sintering a laminate of a green sheet provided with an opening by punching and a flat green sheet in which metal particles to be a wiring pattern are arranged on the front and back surfaces. Examples of the main component of the green sheet include Al2O3 powder and AlN powder.

  Furthermore, a metal base substrate can be used. In this case, the concave portion is formed by any of end mill, rolling, pressing, etching, or a combination thereof.

  As described above, not only a case made of a single material but also a top surface and side surfaces (hereinafter referred to as a reflector) and a bottom portion (hereinafter referred to as a mount) are formed as separate members, and then the reflector and You may use the case which consists of a composite material which adhere | attached the mount.

  For example, reflector materials include metals such as Al alloys and Fe alloys, thermoplastic resins such as polyphthalamide resins and liquid crystal polymers, and thermosetting resins such as epoxy resins, modified epoxy resins, silicone resins, and modified silicone resins. Resin. On the other hand, examples of the mount material include an alumina substrate having a wiring pattern formed on the front and back surfaces, a ceramic substrate such as aluminum nitride, a glass epoxy substrate, a resin mixed lead frame, and a metal base substrate.

  When a resin is used for the case, reflector, and mount, it is preferable that the resin contains a white pigment such as TiO2, BaSO4, Al2O3, ZnO, or BN in order to improve reflectivity. Of these, it is preferable to use TiO 2 which is inexpensive and excellent in weather resistance and chemical stability.

  Moreover, it is preferable to form a reflection made of one or more metals selected from Al, Ag, Cr, Pd or the like or an alloy thereof on the inner surface of the reflector. Of these, it is preferable to use an Al or Al alloy that is inexpensive and excellent in chemical stability.

(Phosphor)
Various selections are possible for the phosphor particles used in the embodiments of the present invention.

  For example, when used in combination with a purple LED chip, is it used in combination with blue phosphor particles and yellow phosphor particles or in combination with blue phosphor particles, yellow phosphor particles and red phosphor particles from the viewpoint of color rendering properties? It is preferable to use in combination with blue phosphor particles, green phosphor particles and red phosphor particles.

  Further, when used in combination with a blue LED chip, from the same viewpoint as described above, it is used in combination with yellow phosphor particles, in combination with yellow phosphor particles and red phosphor particles, or green phosphor particles and red phosphor. It is preferable to use in combination with particles.

  Further, when used in combination with a plurality of types of LED chips, for example, when used in combination with a blue LED chip and a green LED chip, it is preferable to combine with a red phosphor, and when used in combination with a blue LED chip and a red LED chip, green fluorescence. It is preferable to combine with body particles or yellow phosphor particles.

  The average particle diameter of the phosphor is preferably 1 μm to 30 μm in consideration of the escape from the opening of the mask.

Examples of the blue phosphor particles (peak wavelength: 450 nm to 495 nm) include the following fluorescent materials.
(Ba, Sr) MgAl10O17: Eu2 +
(Ba, Ca, Mg) 5 (PO4) 3Cl: Eu2 +
(Ca, Sr, Ba) 2SiS4: Ce3 +
(Ca, Sr, Ba) 10 (PO4) .Cl2: Eu2 +

Examples of the green phosphor particles (peak wavelength: 495 nm to 570 nm) include the following fluorescent materials.
Si6-zAlzOzN8-z: Eu2 + (where 0 <z ≦ 4.2)
(Ca, Sr, Ba) Si2O2N2: Eu2 +
Y3 (Al, Ga) 5O12: Ce3 +
(Sr, Ba) 2SiO4: Eu2 + (where Sr coefficient <Ba coefficient)
(Sr, Ba) 3SiO5: Eu2 + (where Sr coefficient <Ba coefficient)
(Ca, Sr, Ba) Ga2S4: Eu2 +

Examples of yellow phosphor particles (peak wavelength: 570 nm to 590 nm) include the following fluorescent materials.
Y3Al5O12: Ce3 +
(Sr, Ba) 2SiO4: Eu2 + (where Sr coefficient> Ba coefficient)
(Sr, Ba) 3SiO5: Eu2 + (where Sr coefficient> Ba coefficient)
(Ca, Mg) x (Si, Al) 12 (O, N) 16: Eu2 + (where 0 <x ≦ 2)

Examples of the red light conversion phosphor (peak wavelength: 590 nm to 700 nm) include the following phosphors.
(Ca, Sr, Ba) AlSiN3: Eu2 +
(Ca, Sr, Ba) 2Si5N8: Eu2 +
(Y, Gd) 3Al5O12: Ce3 +
(Y, La) O3: Eu2 +
(Ca, Sr) S: Eu2 +

  When using a combination of multiple types of phosphor particles, from the viewpoint of reducing manufacturing costs, it is possible to apply these phosphor particles as a mixed liquid and volatilize the volatile solvent to form a single layer structure. preferable. This is because the application can be performed collectively. On the other hand, from the viewpoint of excitation efficiency, it is preferable to apply as a mixed solution in which the phosphor particles emitting wavelength-converted light on the long wavelength side are sequentially mixed and volatilize the volatile solvent to obtain a laminated structure. A phosphor that emits long-wavelength converted light by arranging phosphor particles that emit long-wavelength wavelength-converted light on the LED chip side, and phosphor particles that emit wavelength-converted light of short wavelength disposed above this This is because it is not re-excited by the wavelength-converted light of the particles.

(Volatile solvent)
Examples of the volatile solvent used in the embodiment of the present invention include alcohol solvents.
Among alcohol solvents, it is preferable to use terpineol (boiling point: 220 ° C.) that is difficult to evaporate at room temperature and has a relatively low boiling point.

(Mixture)
The liquid mixture in the embodiment of the present invention is a liquid mixture obtained by mixing the above-described phosphor particles in the above-mentioned volatile solvent. In addition, transparent particles such as fused silica, crystalline silica, and glass may be included so that light emitted from the LED chip is transmitted to some extent. When the transparent particles are included, it is preferable that the refractive index difference with the encapsulant is generated, and the light emitted from the LED chip, the wavelength converted light from the phosphor particles, and the encapsulant are mixed positively. . The average particle diameter of the transparent particles is preferably 1 μm to 30 μm in consideration of the escape from the opening of the mask.

  In order for the liquid mixture to be easily applied by screen printing, it is preferable to adjust the ratio of the volatile solvent and the particles to be mixed therein so that the viscosity is 10 Pa · s to 300 Pa · s.

(mask)
As a mask used in the embodiment of the present invention, an etching metal mask that forms an opening by etching in a stainless steel plate material, a laser metal mask that forms an opening by laser processing in a stainless steel plate material, and an opening by electroforming An additive metal mask for forming the provided Ni plate material is exemplified. Among these, it is preferable to use an additive metal mask in which the opening can be easily miniaturized.

  As shown in FIGS. 2 (a) to 2 (d), the opening H has a liquid mixture in a larger range than the outer shape of the LED chip 12 in order to arrange the phosphor particles up to the periphery of the LED chip 12. A shape that can be applied is preferable. For example, as shown in FIGS. 2 (a) and 2 (b), a single circular or square opening H may be associated with one LED chip 12, or FIGS. As shown in (d), a plurality of quadrangles arranged in a lattice shape or hexagonal openings H arranged in a honeycomb shape may be combined to correspond to each other. If the plurality of openings H are provided, the uniformity of the application of the mixed liquid can be further ensured.

(Encapsulant)
Examples of the sealing material used in the embodiment of the present invention include epoxy resin, modified epoxy resin, silicone resin, modified silicone resin, fluororesin, sol-gel glass, and low-melting glass.
Among these, it is preferable to use a silicone resin or a modified silicone resin that is excellent in heat resistance and light resistance and can easily seal the LED chip.

  Next, a method for manufacturing a light-emitting device using the above-described components will be described with reference to the accompanying drawings.

(Case forming process)
As shown in FIG. 3A, a case assembly 11a having a plurality of recesses is formed. A conductor (not shown) such as a lead frame or a wiring pattern is exposed on the bottom surface of each recess of the case assembly 11a, and is electrically connected to the outside from each back surface of the case assembly 16b corresponding to the bottom surface of the recess. It can be done.

(LED chip mounting process)
As shown in FIG. 3B, the LED chip 12 is mounted on the bottom surface of each recess of the case assembly 11a. When the LED chip 12 is a face-up type LED chip, it is electrically connected to the conductor on the bottom surface of the recess through a wire. When the LED chip 12 is a flip chip type LED chip, it is electrically connected to the conductor on the bottom surface of the recess through a metal bump or solder. When the LED chip 12 is an LLO type chip, the electrode on the back surface is electrically connected to the conductor via the solder, and the electrode on the upper surface is electrically connected to the conductor via the wire.

(Mask placement process)
As shown in FIG. 3C, a metal mask M having openings H corresponding to the respective recesses is disposed so as to contact the top surface of the case assembly 11a.

(Mixed liquid application process)
As shown in FIG. 4A, by placing a mixed solution 14 in which phosphor particles are mixed in a volatile solvent on the surface of the metal mask M and moving the squeegee S along the surface of the metal mask M, The mixed solution is applied to the periphery of the LED chip 12 from the opening H of the metal mask.

(Solvent volatilization process)
As shown in FIG. 4B, the volatile solvent of the mixed liquid applied to the periphery of the LED chip 12 is volatilized by heating, so that only the phosphor particles 15 are in contact with the LED chip. The volatile solvent is preferably volatilized at a temperature below the boiling point. This is because the phosphor particles 15 may not be uniformly arranged around the LED chip 12 due to bumping.

(Sealing process)
As shown in FIG.4 (c), after supplying the non-hardened sealing material 16a to each recessed part of the case aggregate 11a with the dispenser D, it is made to harden and an LED chip is sealed with the sealing material 16b.

(Separation process)
As shown in FIG. 4D, the case aggregate 16a is divided into individual cases 16b to obtain a plurality of LED lamps. When the case assembly 16a is a single material made of ceramic, it is divided by snapping. When the case assembly 16a is a single material made of resin or a composite material, the case assembly 16a is divided by dicing.

  According to the LED lamp manufacturing method of the present embodiment, since the mixed solution is applied to the light emitting element mounting portion using screen printing, it is possible to apply the mixed solution all at once, and the manufacturing cost is reduced. In addition, by volatilizing the volatile solvent mixed with the phosphor particles, the phosphor is in close contact with the LED chip, so that a sufficient wavelength conversion rate can be obtained even if the supply amount of the phosphor particles is reduced. The material cost will be low.

  The light-emitting device obtained by the manufacturing method of the present invention includes a top-emitting LED lamp (so-called top-view LED lamp), a side-emitting LED lamp (so-called side-view LED lamp), and a chip-on-board. The present invention is applied to a type LED module (so-called COB type module) and the like, and can be used for various light sources such as illumination and a backlight of a liquid crystal display.

  The present invention is not limited to the description of the embodiment of the invention described above. Various modifications are also included in the present invention as long as those skilled in the art can easily conceive without departing from the scope of the claims.

1 Case 2 LED chip (light emitting element)
5 Phosphor Particles 6 Sealing Material 11a Case Assembly 11b Case 12 LED Chip (Light Emitting Element)
14 Mixture 15 Phosphor Particle 16 Sealing Material M Metal Mask H Opening S Squeegee D Dispenser

Claims (5)

An element mounting step of mounting a light emitting element on the bottom of the recess provided in the case;
A mask placement step of placing a mask provided with an opening corresponding to the mounting portion of the light emitting element on the top surface of the case;
Using the mask, screen-printing a mixed liquid in which phosphor particles are dispersed in a volatile solvent, and applying the mixed liquid around the light-emitting element mounting portion in the recess;
And a solvent volatilization step of volatilizing the volatile solvent of the mixed liquid by heating to volatilize.   The manufacturing method of the light-emitting device according to claim 1, further comprising a sealing step of sealing the light-emitting element by supplying an uncured sealing material into the concave portion and curing after the solvent volatilization step.   3. The method for manufacturing a light emitting device according to claim 2, wherein in the solvent volatilization step, the volatile solvent is volatilized at a temperature not exceeding the boiling point of the volatile solvent.   The method for manufacturing a light emitting device according to any one of claims 1 to 3, wherein the mixed solution further includes transparent particles. The method for manufacturing a light-emitting device according to claim 1, wherein the volatile solvent is an alcohol solvent.

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