JP2003163376A - Wavelength conversion material and light emitting element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a wavelength conversion material and a light emitting element which have excellent permeability for stimulation light and fluorescence and high photothermal durability in which deteriorations of a fluorescent and resin materials are reduced by obtaining a high luminance and highly controlled chromaticity by suitably scattering the light. <P>SOLUTION: The wavelength conversion material contains 1 to 10 wt.% of a fluorescent material and 0.5 to 4 wt.% of at least one of an optical radical scavenger, and an antioxidant to 100 wt.% of a resin material. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength conversion material that emits white light and a light emitting device.

[0002]

2. Description of the Related Art As conventional white semiconductor light emitting devices (LEDs), there are the following technologies.

(1) In a white light emitting element, which is a combination of a blue or blue-violet light emitting diode and one or more phosphors that absorb the light emitted from the light emitting diode and emit light in the visible range, The phosphors are selected so that the emission colors of the phosphors are added to have a complementary color relationship with each other and the phosphors emit white light (JP-A-10-163535).

(2) A white light source having a light emitting diode chip as a light emitting element is subjected to wavelength conversion by using a wavelength conversion material to improve color rendering properties (Japanese Patent Laid-Open No. 11-399).
17 publication). Specifically, the dye rhodamine (Rhod
LED with an epoxy resin in which amin) is dissolved and dispersed.
Cover the chip.

(3) A fluorescent layer having a constant film thickness is formed from an inorganic fluorescent thin film formed by a sputtering method in the shape of an LED chip (JP-A-11-46015).

(4) A phosphor powder which is excited and emitted by blue light of a light emitting diode and a wavelength conversion phosphor substance whose main component is a powder that scatters the excitation light are mixed with an acrylic solvent, and a light introducing part of a pointer is mixed. To obtain white light by applying or printing to a color tone exchange layer (Japanese Patent Application Laid-Open No. 11-248493).
Issue).

(5) A cap containing a fluorescent substance is detachably attached to the light emitting diode to convert the emission color of the LED into white or another desired color. A fluorescent substance, a fluorescent pigment, a fluorescent dye or the like is used as the fluorescent substance (Japanese Patent Laid-Open No. 11-8).
7784).

(6) A light emitting diode is formed on the gallium nitride based semiconductor LED chip, in which a phosphor mixed and dispersed in an epoxy resin is poured and cured to form (JP-A-2000-252523).

(7) As a phosphor, Rhodamin B, Rhodamin 6G, Basic Yel is used on a carrier such as polymethacrylic acid ester.
An organic phosphor in which a dye such as low HG is dissolved is used (JP-A-11-46019).

(8) In addition to this, Eu is used as a phosphor.
It has been proposed to use rare earth complexes such as Tb and Nb (Chemicals and Industry, Vol. 53, No. 2 (2000)).

[0011]

However, each of the above-mentioned conventional techniques has the following problems.

(1) In the technique disclosed in JP-A-10-163535, the phosphor is an inorganic powder,
Visible light scattering was unavoidable, and it was difficult to achieve high brightness.

(2) In the technique disclosed in Japanese Patent Application Laid-Open No. 11-39917, the resin in which the dye is dissolved is poured into the concave portion, which is difficult to process and is difficult to control chromaticity with high accuracy. Further, if the resin in which the dye is dissolved is epoxy alone, the dye is deteriorated by lighting for several hours, and the luminance and chromaticity are reduced.

(3) In the technique disclosed in Japanese Patent Laid-Open No. 11-46015, since the sputtering method is used, a vacuum vapor deposition apparatus is required and expensive equipment is required.

(4) In the technique disclosed in Japanese Patent Application Laid-Open No. 11-248493, there is a distance between the blue excitation light source and the phosphor layer, the excitation light is reduced, and the brightness is reduced.

(5) In the technique disclosed in Japanese Patent Laid-Open No. 11-87784, the cap-shaped phosphor-containing coating is located at a distance from the light source, and it is difficult to increase the brightness because the excitation light is reduced.

(6) In the technique disclosed in Japanese Unexamined Patent Publication No. 2000-252523, the phosphor is poured together with the resin into the two-step recesses and the phosphor is allowed to settle, which makes it difficult to control the chromaticity of light emission.

(7) The techniques disclosed in the above items (7) and (8) are superior in durability to fluorescent dyes containing only organic components, but are dissolved and solidified in PMMA solids. However, there is a problem in operability of processing and mounting on a minute LED surface.

The present invention solves the above-mentioned problems, and has excellent transmissivity for both excitation light and fluorescence, and by appropriate light scattering, it has high brightness and highly controlled chromaticity. In addition, it is an object of the present invention to obtain a wavelength conversion material and a light-emitting device having high photothermal durability and reduced deterioration of the phosphor and the resin material.

[0020]

The present invention provides a resin material 10
The fluorescent material was contained in an amount of 1 to 10 wt% and 0.5 to 4 wt% of at least one of a photo radical scavenger, a heat radical scavenger, and an antioxidant with respect to 0 wt%.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION In the invention described in claim 1, 1 to 10 wt% of a fluorescent material, and at least one of a photo radical scavenger, a heat radical scavenger, and an antioxidant are added to 100 wt% of a resin material. By using a wavelength conversion material characterized by containing 0.5 to 4 wt%, it is possible to reduce deterioration due to at least one of light, heat and oxidation in at least one of the fluorescent material and the resin material. It is possible to prevent deterioration of characteristics due to long-term use and to achieve long life.

According to a second aspect of the present invention, at least one of an acrylic resin, a thermosetting alicyclic epoxy resin, and a photocurable alicyclic epoxy resin is used as the resin material. By using the wavelength conversion material of (1), the coating property and the like are good, the durability is to some extent, and the productivity is good.

The invention of claim 3 is characterized in that a hindered amine is used as a photo radical scavenger, a hindered phenol is used as a heat radical scavenger, and a phenolic antioxidant is used as an antioxidant. By using the described wavelength conversion material, the characteristic deterioration of the resin material or the fluorescent material can be surely suppressed.

According to the invention of claim 4, as the fluorescent material, an organic fluorescent substance comprising a compound containing at least one aromatic cyclic molecule in one molecule, or at least one typical or transmissive compound in one molecule. Focusing on metal ions,
The wavelength conversion material according to claim 1, wherein at least one of the organometallic complex phosphors made of a compound having an organic molecule or an inorganic molecule as a ligand is used.
It is possible to perform stable wavelength conversion.

The invention according to claim 5 is provided with a light source and a wavelength conversion portion that covers at least a light emitting portion of the light source, and the wavelength conversion portion is the wavelength conversion material according to any one of claims 1 to 4. By using the light-emitting element characterized by being configured as above, deterioration of the characteristics of the wavelength conversion unit can be prevented, and the wavelength of the emitted light does not change even after long-term use.

According to a sixth aspect of the present invention, the light source is a chip light source, and the chip light source is mounted so as to be electrically connected to an electrode pattern provided on the substrate. By using the light emitting device described above, the light source can be mounted on the substrate by surface mounting, which improves productivity and is a preferable form for mass production.

According to a seventh aspect of the present invention, the light emitted from the light source is blue light or light having a wavelength shorter than blue light. It becomes possible to emit light.

The invention according to claim 8 is characterized in that the wavelength conversion part converts a part of the wavelength of the light emitted from the light source to the long-wavelength side.
Since it can efficiently emit haiku-colored light, it can be used for displays, backlights and lighting.

According to a ninth aspect of the present invention, the light source is an LED containing gallium nitride.
By using the light-emitting element described above, it is possible to easily emit light having a short wavelength of blue or more and to be environmentally friendly.

According to a tenth aspect of the present invention, the light source is embedded in the wavelength conversion section, whereby the light emitting element according to the fifth aspect is reliably covered with the wavelength conversion section. Since it can be realized easily by coating or printing, the productivity is also improved.

FIG. 1 shows an embodiment of the present invention.
Will be explained.

(Embodiment) FIG. 1 is a sectional view showing a structure of a light emitting device according to an embodiment of the present invention. In FIG. 1, 1 is an LED substrate having a Zener diode, and 2 is a G substrate.
An LED chip (semiconductor light-emitting device) having an aN-based compound, and the LED chip 2 preferably emits light having a short wavelength of blue or more. 3 is L
Bumps for connecting the anode wiring and the cathode wiring formed on the ED substrate 1 to the electrodes of the LED chip 2,
Reference numeral 4 denotes a wavelength conversion portion which is covered so as to cover the entire circumference of the LED chip 2. As a means for connecting the anode wiring and the cathode wiring to the electrodes of the LED chip 2, a mounting method using a wire can be used in addition to the flip-chip mounting using bumps. Further, the wavelength conversion unit 4 is L
Since the light emitting portion of the LED chip 2 can be surely covered by being configured to cover the entire circumference of the ED chip 2, the productivity is improved, but at least a part or all of the light emitting portion of the LED chip 2 is improved. It is possible to obtain a sufficient effect by providing the above.

An example of the manufacturing process of this light emitting device will be described with reference to the process diagram showing the manufacturing process of the light emitting device in the embodiment of the present invention shown in FIG. As shown in FIG. 2A, the LED chip 2 is formed on the LED substrate 1 by a process such as flip chip bonding (FCB) or wire bonding, and the LED chip 2 is formed on the LED substrate 1 by the bumps 3. It is fixed in a floating state.

Next, as shown in FIG. 2B, a wavelength converting material is formed on the LED substrate 1 so as to cover the entire circumference of the LED chip 2, and the wavelength converting portion 4 is formed.

Next, as shown in FIG. 2C, the upper surface of the formed wavelength conversion portion 4 is rotationally ground by the grinding tool 10.

Finally, as shown in FIG. 2D, dicing is performed by the cutter 11 to cut into individual LED elements.

Through the above steps, the wavelength conversion unit 4 is the LED
Formed around the chip 2.

As a method of forming the wavelength conversion section 4 of FIG. 2B, the following method can be used.

(1) Screen printing method This is a method of pattern-printing a paste-like wavelength conversion material through a mask.

(2) Inkjet method This is a method of spraying an ink-like wavelength conversion material by a method such as heating, compression and voltage application.

(3) Electrostatic adsorption method This is a method for charging a powder (solid) wavelength conversion material to L
It is electrostatically adsorbed on the upper surface of the ED chip 2 and then coated.

(4) Dispersion method in resin This is potting of a wavelength converting material having fluidity,
Perform by pouring.

(5) LB method This is a method in which a fluorescent material is made to be bipolar and surface-active by giving surface activity to form a monomolecular film, and the film is pulled up by an LED substrate and simultaneously attached.

(6) Casting method In this method, a fluid wavelength conversion material in which a fluorescent material is dissolved and dispersed is cast (dropped) to be formed, and the substrate is rotated to form a thin film.

(7) Film sticking method In this method, a film-shaped wavelength conversion material is stuck and the chip LEDs are cut together.

(8) Sedimentation method This is a method of injecting a resin into the concave portion and allowing the fluorescent material solid to settle there.

(9) Vapor deposition method This is a method of thinning the wavelength conversion portion to a film thickness of 5 nm to 5 μm, and the vacuum vapor deposition method is desirable from the viewpoints of being homogeneous and not easily generating pinholes. When this vapor deposition method is used for thinning, it depends on the type of dye compound used, the desired crystal structure of the molecular deposited film, and the associated structure.

[0048]

EXAMPLES Examples of the present invention will be described below with respect to the wavelength conversion material forming the wavelength conversion section 4 described above.

(Example 1) An example in which the wavelength conversion material is an organic compound will be described. As an organic compound, 1
A compound containing at least one aromatic cyclic molecule in the molecule is used. This compound includes perylene, coumarin,
There are Eosin, Rhodamine 6G, etc.

The chemical formulas of these compounds are as follows.

[0051]

[Chemical 1]

[0052]

[Chemical 2]

[0053]

[Chemical 3]

[0054]

[Chemical 4]

By containing at least one aromatic cyclic molecule, these compounds act as a source of photoelectrons that transit when the aromatic cyclic molecule emits fluorescence, and
The effect of being excited by light from the ED chip and emitting fluorescence of longer wavelength is obtained.

Next, an example in which the wavelength conversion section 4 is an organometallic complex will be described. As the organometallic complex, a compound having at least one typical or transition metal ion in the molecule as a center and an organic molecule or an inorganic molecule as a ligand is used. This compound includes Eu (TTA) ₃ Phe
n, Tb (acac) ₃ Phen and the like.

The chemical formulas of these compounds are as follows.

[0058]

[Chemical 5]

[0059]

[Chemical 6]

In these compounds, by including a compound having at least one typical or transition metal ion as a center in one molecule and an organic molecule or an inorganic molecule as a ligand, the ligand has a central metal. It has the effect of attracting or withdrawing electrons to the ligand side, affecting the transition electrons of the central metal, and emitting fluorescence. Next, examples of the resin carrying the wavelength conversion material will be described.

[0061]

[Chemical 7]

[0062]

[Chemical 8]

[0063]

[Chemical 9]

Among these resins, (Chemical formula 7) is a typical thermoplastic resin (for example, polymethylmethacrylic acid resin (acrylic)), and (Chemical formula 8) is a typical thermosetting resin (for example, alicyclic). Epoxy resin (thermosetting),
(Chemical Formula 9) is a typical photocurable resin (for example, alicyclic epoxy resin (photocurable)). The chemical formula 7 does not contain a radically active curing agent, and has an effect of preventing the dye from being deteriorated by radicals activated by light and heat. In (Chemical Formula 8), the pot life is long and the effect that fine processing can be performed is obtained. With (Chem. 9), it is possible to obtain an effect that precision processing is performed even when performing fine processing in a short time by light irradiation at room temperature.

In this embodiment, each of the above resin materials is used one by one, but the resin materials may be mixed, and the resin material composed of at least one of the above resin materials may be mixed. Other resin materials and inorganic materials may be added to the extent that they do not affect the light emission characteristics and the like.

[0066]

[Chemical 10]

[0067]

[Chemical 11]

[0068]

[Chemical 12]

In these compounds, (Chemical Formula 10) is a typical photo-radical scavenger (for example, hindered amine), which traps radical electrons generated in the system to lose the activity and obtain the photostability of the dye. The effect is obtained. (Chemical Formula 11) is a typical heat radical scavenger (for example, hindered phenol), which has the effect of trapping radical electrons generated in the system by heat to lose activity and obtain the photostability of the dye. . (Chemical Formula 12) is a typical antioxidant (phenolic antioxidant), which has an effect of trapping radical electrons generated in the system to lose its activity and preventing deterioration of the dye and the resin. In the present embodiment, the photo radical scavenger, the heat radical scavenger, and the antioxidant (hereinafter abbreviated as stabilizers) are all provided in the resin material. May include at least one.

For example, when a white semiconductor light emitting device is produced, the organic fluorescent material represented by the above (Chemical formula 1) to (Chemical formula 6) is used in the above (Chemical formula 7) within a weight ratio range of 1 to 10 wt%. ) To (Chemical Formula 9) resin material represented by 100 wt%
Disperse into At this time, the photo radical scavenger, the heat radical scavenger, or the antioxidant represented by (Chemical Formula 10) to (Chemical Formula 12) is added in a range of 0.5 to 4 wt% by weight, respectively. If the amount of the organic fluorescent material is less than 1 wt%, sufficient wavelength conversion characteristics cannot be obtained, and if it exceeds 10 wt%, the light amount may be reduced. Further, if the amount of the stabilizer is less than 0.5 wt%, sufficient deterioration of the resin material or the fluorescent material cannot be prevented, and if it is 4 wt% or more, the light amount may be reduced.

A paste or the like of the wavelength conversion material obtained by adding these is applied to the upper surface of the LED chip 2 serving as an excitation light source in a thickness range of 10 to 200 μm,
It is sufficiently dried to produce the wavelength conversion section 4. At this time, if the film thickness of the wavelength conversion unit 4 is smaller than 10 μm, the LED will be sufficient.
It becomes difficult to sufficiently convert the wavelengths of light from the chips 2 to 2. When the film thickness exceeds 200 μm, a large amount of light is absorbed by the wavelength conversion unit 4, and the amount of light cannot be expected.

These (formula 10), (formula 11), and (formula 1)
FIG. 3 shows the emission spectrum of the light emitting device when the compound of 2) was added to the resin. The peak on the short wavelength side is due to blue excitation light, and the peak on the long wavelength side is emitted from the fluorescent material. Part of the blue excitation light excites the fluorescent material and is converted into longer-wavelength fluorescence to emit light. The remaining excitation light is emitted to the outside in the blue color.
If the fluorescence converted by the fluorescent material is a complementary color of the original excitation light, the combined light becomes white light. As shown in FIG. 3, after adding (Chemical Formula 10), (Chemical Formula 11), and (Chemical Formula 12), it can be seen that the wavelengths of the two peaks in the spectrum do not fluctuate and white light emission is maintained. .

FIG. 4 shows changes with time in the emission intensity of long-wavelength side fluorescent light during continuous lighting of the fluorescent material. The compounds of (Chemical formula 10), (Chemical formula 11) and (Chemical formula 12) were added to the resin. The effect of the change over time is shown. (Chemical formula 10) / (Chemical formula 11) / (Chemical formula 12)
It can be seen that in the system in which is added, the fluorescence emission of the long wavelength side remains longer.

FIG. 5 shows these (formula 10), (formula 11), and
It shows the lifetime of the emission intensity when the compound of Chemical formula 12 is added. As can be seen from FIGS. 4 and 5, it is understood that the emission lifetime and the intensity are increased by adding the stabilizer.
It can be seen that the addition of (Chemical formula 10) increases the emission lifetime of long-wavelength fluorescence by about 2 times, and the addition of (Chemical formula 11) and (Chemical formula 12) extends by about 8 times or more.

[0075]

According to the present invention, 1 to 10 wt% of the fluorescent material and 0.5 to 0.5 wt% of the photo radical scavenger, the heat radical scavenger and the antioxidant are added to 100 wt% of the resin material.
By containing ~ 4 wt%, it is possible to reduce the deterioration of at least one of the fluorescent material and the resin material due to at least one of light, heat, and oxidation, so that the deterioration of the characteristics due to long-term use can be prevented. , Long life can be realized.

Further, by adopting a structure in which the electrode pattern on the substrate and the electrode of the LED chip are connected via the bump, the manufacturing method using the flip chip method can be applied.

At least one wavelength conversion material is used in one molecule.
By using an organic phosphor made of a compound containing individual aromatic cyclic molecules, the organic phosphor can be easily dissolved and dispersed in a solvent, a resin, or the like.

At least one wavelength conversion material is used in one molecule.
Dissolving in a solvent, a resin, etc. by using an organometallic complex phosphor composed of a compound having an organic molecule or an inorganic molecule as a ligand, centered on individual typical or transition metal ions,
Dispersion becomes easy.

[Brief description of drawings]

FIG. 1 is a sectional view showing a structure of a light emitting device according to an embodiment of the present invention.

FIG. 2 is a process drawing showing a manufacturing process of a light emitting device according to an embodiment of the present invention.

FIG. 3 is a diagram showing a spectrum of emission characteristics of a light emitting device according to an embodiment of the present invention.

FIG. 4 is a graph showing changes over time in light emission of the light emitting element according to the embodiment of the present invention.

FIG. 5 is a graph showing a fluorescence intensity lifetime of a light emitting device according to an embodiment of the present invention.

[Explanation of symbols]

1 LED board 2 LED chips 3 bumps 4 Wavelength converter 10 grinding tools 11 cutter

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Megumi Sakagami             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5F041 AA11 AA43 AA44 CA40 DA44                       DA46

Claims (10)

[Claims] 1. A fluorescent material in an amount of 1 to 10 wt% and at least one of a photo radical scavenger, a heat radical scavenger, and an antioxidant in an amount of 0.5 to 4 wt% with respect to 100 wt% of a resin material. A wavelength conversion material characterized in that 2. The wavelength conversion material according to claim 1, wherein at least one of an acrylic resin, a thermosetting alicyclic epoxy resin, and a photocurable alicyclic epoxy resin is used as the resin material. 3. The wavelength conversion material according to claim 1, wherein a hindered amine is used as a photo radical scavenger, a hindered phenol is used as a heat radical scavenger, and a phenolic antioxidant is used as an antioxidant. . 4. An organic fluorescent substance comprising a compound containing at least one aromatic cyclic molecule in one molecule, or at least one typical or transfer metal ion in one molecule. 2. The wavelength conversion material according to claim 1, wherein at least one of organometallic complex phosphors made of a compound having an organic molecule or an inorganic molecule as a ligand is used. 5. A light source, and a wavelength conversion section that covers at least a light emitting portion of the light source, wherein the wavelength conversion section is defined by claim 1.
[4] A light emitting device comprising the wavelength conversion material according to any one of [4] to [4]. 6. The light emitting device according to claim 5, wherein the light source is a chip light source and is mounted so as to electrically connect electrodes of the chip light source to an electrode pattern provided on a substrate. 7. The light emitting device according to claim 5, wherein the light emitted from the light source is blue or light having a wavelength shorter than blue. 8. The wavelength conversion unit converts a part of the wavelength of the light emitted from the light source to the long wavelength side.
The light emitting device described. 9. The light emitting device according to claim 7, wherein the light source is an LED containing gallium nitride. 10. The light emitting device according to claim 5, wherein a light source is embedded in the wavelength conversion section.