JP2007123390A - Light emitting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light emitting device which can suppress the moisture transmission of a matrix layer and keep light emission efficiency for a long time. <P>SOLUTION: The light emitting device 1 is provided with a light emitting element 7 which is arranged on a substrate 3 to emit excitation light, and a matrix layer 9 which is formed to cover the light emitting element 7 and formed mainly of a resin 13. In this case, the matrix layer 9 contains a nonfluorescent moisture absorbent 15. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light-emitting device that uses light emitted from a light-emitting element, and more particularly to a light-emitting device that is suitably used for a backlight power source for an electronic display, a fluorescent lamp, or the like.

  A light emitting element made of a semiconductor material (hereinafter referred to as an LED chip) is small in size, has high power efficiency, and vividly develops color. LED chips have excellent characteristics such as long product life, strong on / off lighting repeatability, and low power consumption, so they are expected to be applied to backlight sources such as liquid crystals and lighting sources such as fluorescent lamps. Has been.

  The application of the LED chip to the light emitting device is, for example, by converting a part of the light of the LED chip with a phosphor and mixing and emitting the wavelength-converted light and the light of the LED that is not wavelength-converted. It has already been realized as a light emitting device that emits a color different from that of LED light.

Specifically, in order to emit white light, a light emitting device in which a wavelength conversion layer containing a phosphor is provided on the surface of an LED chip has been proposed. For example, in a light emitting device in which a matrix layer including a YAG phosphor expressed by a composition formula of (Y, Gd) ₃ (Al, Ga) ₅ O ₁₂ is formed on a blue LED chip using an nGaN-based material, Since blue light is emitted from the chip and a part of the blue light is changed to yellow light in the matrix layer, a light emitting device in which blue and yellow light are mixed to present white has been proposed (for example, see Patent Document 1). ).

  In addition, even when a phosphor is not used in this way, a matrix layer is formed so as to cover the surface of the LED chip in order to protect the LED chip from the environment.

  The matrix layer is required to have a high light transmittance since it has a role of protecting the LED chip and a function of taking out the light from the LED chip to the outside without blocking as much as possible.

  For this reason, for example, in a PKG containing a semiconductor element, a potting agent having a large amount of inorganic particles and having excellent water resistance has been used. However, since such a potting agent has poor light transmission, It is not suitable as a matrix layer.

  For this reason, although the matrix layer is formed of an epoxy resin or a silicone resin, the moisture cannot be sufficiently blocked.

As countermeasures, for example, improvements such as mixing isobutylene having a low moisture permeability with a silicone resin are performed (for example, see Patent Document 2).
JP 11-261114 A JP 2000-136275 A

  However, since isobutylene has a double bond, it absorbs light in the ultraviolet region, and there is a possibility that the light transmission property is deteriorated or the resin is easily deteriorated.

  Accordingly, an object of the present invention is to provide a light emitting device that suppresses moisture permeation through a matrix layer and maintains luminous efficiency for a long period of time.

  A light-emitting device of the present invention is a light-emitting device including a light-emitting element that emits excitation light disposed on a substrate, and a matrix layer mainly composed of a resin that is formed so as to cover the light-emitting element, The matrix layer contains a non-fluorescent hygroscopic agent.

  In the light-emitting device of the present invention, it is preferable that a phosphor that converts excitation light into visible light is dispersed in the matrix layer.

  In the light emitting device of the present invention, the phosphor is preferably semiconductor nanoparticles.

  In the light emitting device of the present invention, it is desirable that the moisture absorbent has a high content on the surface side of the matrix layer.

  In the light emitting device of the present invention, it is preferable that the phosphor has a low content on the surface side of the matrix layer.

  In the light emitting device of the present invention, it is desirable that the hygroscopic agent is silica gel.

  In the light emitting device of the present invention, it is desirable that the hygroscopic agent is zeolite.

In the light emitting device of the present invention, it is desirable that the hygroscopic agent has a BET specific surface area of 50 m ² / g or more.

  In the light emitting device of the present invention, the resin preferably contains a silicone resin.

  In the light-emitting device of the present invention, it is desirable that a moisture-proof layer having a lower water absorption rate than the matrix layer is formed so as to cover the matrix layer.

In the light-emitting device of the present invention, it is preferable that the moisture permeability of the moisture-proof layer is 1 g / m ² · day or less.

  Moreover, as for the light-emitting device of this invention, it is desirable for the thickness of the said moisture-proof layer to be 1-1000 micrometers.

  In the light-emitting device of the present invention, it is desirable that the moisture-proof layer is made of one selected from the group consisting of a composite material of glass and ceramics, glass, ceramics and single crystals.

  The light-emitting device of the present invention is a light-emitting device including a matrix layer mainly composed of a resin formed so as to cover the light-emitting element, and a moisture absorbent is dispersed in the matrix layer so that the matrix layer is externally provided in the matrix layer. The moisture that has entered can be trapped with a hygroscopic agent to prevent deterioration of the resin that forms the matrix layer, and short-circuiting and migration at the electrodes when used for a long time.

  In addition, according to the light emitting device of the present invention, the phosphor that converts excitation light into visible light is dispersed in the matrix layer, thereby enabling photoluminescence by the matrix layer, and excitation of light emitting elements such as LEDs as the light emitting device. Wavelengths other than light can be easily obtained.

  Moreover, luminous efficiency can be improved by using the semiconductor nanoparticle excellent in the light transmittance as fluorescent substance. In addition, even when using semiconductor nanoparticles whose characteristics are likely to deteriorate due to moisture, according to the present invention, since it is possible to avoid contact with moisture due to the hygroscopic agent, it is possible to prevent a decrease in light emission output, which is excellent in luminous efficiency, Moreover, the light emitting device has a long life.

  Moreover, the light emitting device of the present invention can suppress the contact between moisture and the phosphor by rapidly trapping moisture that has entered the matrix layer by increasing the content of the hygroscopic agent on the surface side of the matrix layer.

  In addition, the light emitting device of the present invention can further suppress the contact between moisture and the phosphor that has entered the matrix surface by reducing the phosphor content on the surface side of the matrix layer, and has a much longer life. It becomes a light emitting device.

  In addition, the light emitting device of the present invention can form a cheap and highly transparent matrix layer by using silica gel as a hygroscopic agent.

  In the light emitting device of the present invention, zeolite has a hole that can be captured by water molecules due to its molecular structure, and can absorb a large amount of moisture. Since more water can be adsorbed than silica gel in terms of molecular structure, the use of zeolite as the hygroscopic agent can sufficiently prevent water diffusion into the matrix even when the content of the hygroscopic agent is reduced.

In addition, according to the present invention, in particular, by using a hygroscopic agent having a BET specific surface area of 50 m ² / g or more, it is possible to prevent moisture diffusion into the matrix by taking it into the moisture absorbent that has entered the matrix layer.

  In addition, according to the present invention, by including a silicone resin as a resin, a matrix layer with little light deterioration and excellent heat resistance is obtained.

  Further, the light emitting device of the present invention can further suppress the intrusion of moisture from the surface by disposing a moisture-proof layer having a low water absorption rate outside the matrix layer. Therefore, contact between the phosphor and moisture can be avoided, and a decrease in light emission output can be prevented.

Further, according to the present invention, the moisture permeability of the moisture-proof layer is suppressed to 1 g / m ² · day or less, and a moisture-proof layer having a water vapor permeability similar to that of a metal foil is used. The amount of water reaching the inner matrix layer can be greatly reduced.

  In the light emitting device of the present invention, by setting the thickness of the moisture-proof layer to 1 μm or more, a stable moisture-proof ability can be obtained even if a defect occurs in the moisture-proof layer or the thickness varies. In addition, by making the thickness of the moisture-proof layer that absorbs light thinner than 1000 μm, light from the light-emitting element or the phosphor can be efficiently taken out of the light-emitting device.

  Further, in the light emitting device of the present invention, by using one kind selected from the group of glass and ceramics composites, glass, ceramics and single crystals as the moisture-proof layer, for example, moisture-proofing excellent in translucency. Layers can be easily formed. In addition, since the thermal expansion coefficient of these materials can be easily controlled, the difference in thermal expansion between the matrix layer and the substrate used in the light emitting device and the moisture-proof layer can be reduced. For this reason, the crack and peeling by a thermal expansion difference can be prevented. Therefore, even if it is exposed to a thermal cycle, the intrusion of moisture can be sufficiently suppressed.

  As shown in FIG. 1, the light emitting device 1 of the present invention includes, for example, a substrate 3, an electrode 5 formed on or inside the substrate 3, and an LED that emits excitation light disposed on the substrate 3. And a matrix layer 9 mainly composed of a resin formed so as to cover the light emitting element 7. The light emitting element 7 and the electrode 5 are electrically connected by bumps 6 such as solder and gold. It is connected to the. Alternatively, the light emitting element 7 and the electrode 5 may be connected by a gold wire or an aluminum wire. In the light emitting device 1 of the present invention, a reflector 11 for reflecting and condensing light from the light emitting element 7 may be formed so as to surround the light emitting element 7.

  According to the present invention, the matrix layer 9 is mainly composed of the resin 13 and contains the non-fluorescent hygroscopic agent 15, and the moisture permeation of the matrix layer 9 can be suppressed by the hygroscopic agent 15. As a result, the matrix layer 9, the electrode 5, the bump 6, the gold wire, and the aluminum wire can be prevented from being deteriorated by the influence of moisture.

  As shown in FIG. 2, when the matrix layer 9 includes a phosphor 17 that converts the wavelength of the excitation light emitted from the light emitting element 7, light other than the wavelength of the excitation light of the light emitting element 7 is emitted. The light emitting device 1 can be easily manufactured. For example, the light emitting device 1 that emits white light can be manufactured.

  Further, as shown in FIG. 3, light emission is achieved by increasing the content of the moisture absorbent 15 in the matrix layer 9 b far from the light emitting element 7 than in the matrix layer 9 a near the light emitting element 7 in the matrix layer 9. Water can be effectively trapped in a region far from the element 7 and the electrode 5.

  In addition, as shown in FIG. 3, the phosphor content of the matrix layer 9b farther from the light emitting element 7 is made lower than the matrix layer 9a closer to the light emitting element 7 in the matrix layer 9, thereby reducing the light emitting element. 7 and the phosphor 17 can be close to each other, so that the light from the light emitting element 7 can be effectively absorbed by the phosphor 17. Further, when the phosphor 17 is made of a material that easily deteriorates due to moisture, moisture can be effectively trapped in a region far from the phosphor 17.

  Further, as shown in FIG. 4, a moisture-proof layer 19 having a lower water absorption rate than that of the matrix layer 9 may be provided outside the matrix layer 9.

  The moisture-proof layer 19 is desirably formed of one kind selected from the group consisting of a glass-ceramic composite material, glass, ceramics, and single crystal. Among these, a glass that is excellent in translucency and inexpensive is used. It is desirable to use it.

Further, when the moisture-proof layer 19 made of ceramic is used, in order to improve the light transmissivity, Al ₂ O ₃ , SiO ₂ , Y ₂ O ₃ , MgO, CaO, BeO, ZrO ₂ , HfO ₂ , It is desirable to contain at least one selected from ThO ₂ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , and MgAlO ₄ .

  As the hygroscopic agent 15 used in the light-emitting device 1 of the present invention having the various modes described above, a material having a function of absorbing moisture in addition to silica gel and zeolite is preferably used.

  The hygroscopic agent 15 having a function of absorbing moisture can be roughly classified into a chemical adsorption type and a physical adsorption type.

Chemisorption types include alkaline earth metal oxides, calcium oxide (CaO), barium oxide (BaO), magnesium oxide (MgO), strontium oxide (SrO) phosphorus pentoxide, anhydrous sodium sulfate, magnesium perchlorate, hydrogenation Calcium, strontium hydride, aluminum hydride, lithium sulfate (Li ₂ SO ₄ ), sodium sulfate (Na ₂ SO ₄ ), calcium sulfate (CaSO ₄ ), magnesium sulfate (MgSO ₄ ), cobalt sulfate (CoSO) ₄ ), gallium sulfate (Ga ₂ (SO ₄ ) ₃ ), titanium sulfate (Ti (SO ₄ ) ₂ ), nickel sulfate (NiSO ₄ ), and the like.

  The chemical adsorption type has a feature of strong water absorption, but generally has a strong toxicity, is difficult to handle, and has a problem in that it is dangerous when recycled. In addition, it is deliquescent, and when it absorbs moisture, it flows out as a liquid. Therefore, when it is used in a small device such as an electronic device, it is necessary to devise confinement so that it does not flow out. In addition, there is a problem that the wiring and the like corrode if the liquid material leaks. Moreover, the thing which swells, when water | moisture content is absorbed, a volume becomes large and it is necessary to ensure a space beforehand and it is not suitable for size reduction. Moreover, it is often highly alkaline and may corrode the substrate and the surrounding area.

  The organic substance is a vinyl polymer of any one of polystyrene, polyacrylonitrile, polyacrylate, polymethacrylate, sulfonic acid group, carboxylic acid group, phosphoric acid group, or a metal salt thereof. A crosslinked polymer having at least one kind of hydrophilic group and crosslinked with either divinylbenzene, triallyl isocyanate or hydrazine is desirable.

  On the other hand, examples of the physical adsorption type include zeolite, activated carbon, silica gel, and grafted starch. Among the physical adsorption types, silica gel and zeolite have a high water adsorption ability. For a light emitting device, it is desirable to use a physical type from the viewpoint of stability.

  In particular, since silica gel is relatively inexpensive and readily available, and also has excellent light-transmitting properties in addition to excellent hygroscopicity, it is very excellent as the hygroscopic agent 15.

Further, zeolite has a very high moisture absorption performance per mass and can maintain a high water absorption capability even in a high temperature atmosphere. Therefore, zeolite is suitable for a power LED having a high calorific value, and silica gel is suitable for the matrix layer 9 having a small LED heat generation. When the specific surface area of the hygroscopic agent 15 is increased, the hygroscopic ability is improved. Therefore, the specific surface area of the hygroscopic agent 15 is preferably 50 m ² / g or more, particularly preferably 100 m ² / g or more, and more preferably 200 m ² / g or more. .

As the phosphor 17, for example, an oxide-based or ZnS-based phosphor having an average particle diameter of about 1 to 20 μm such as (Ba, Eu) MgAl ₁₀ O ₁₇ can be used.

  Further, when semiconductor nanoparticles such as CdSe are used as the phosphor 17, since the semiconductor nanoparticles do not hinder the passage of light, the matrix layer 9 is excellent in light transmissivity, and has high luminous efficiency and moisture content. Thus, the light emitting device 1 in which the deterioration of characteristics due to is suppressed is obtained. It is desirable from the viewpoint of light emission efficiency that the semiconductor nanoparticles have a mean particle size of 10 nm or less. The semiconductor nanoparticles can control the emission wavelength by the band gap energy of each size by the quantum effect. The wavelength of light excited by the semiconductor nanoparticles is synthesized, covering the emission wavelength in a wide range, and the color rendering can be greatly improved. It is desirable from the viewpoint of light emission efficiency that the semiconductor nanoparticles have a mean particle size of 10 nm or less.

Semiconductor nanoparticles as the phosphor 17 contained in the matrix layer 9 are a compound of a periodic table group 14 element and a periodic table group 16 element, a compound of a periodic table group 13 element and a periodic table group 15 element, Compound of Periodic Table Group 13 Element and Periodic Table Group 16 Element, Periodic Table Group 13 Element and Periodic Table Group 17 Element, Periodic Table Group 12 Element and Periodic Table Group 16 Element A compound of a periodic table group 15 element and a periodic table group 16 element, a compound of a periodic table group 11 element and a periodic table group 16 element, a periodic table group 11 element and a periodic table group 17 element Compound, compound of periodic table group 10 element and periodic table group 16 element, compound of periodic table group 9 element and periodic table group 16 element,
Compound of periodic table group 8 element and periodic table group 16 element, periodic table group 7 element and periodic table group 16 element, periodic table group 6 element and periodic table group 16 element A compound of a periodic table group 5 element and a periodic table group 16 element, a compound of a periodic table group 4 element and a periodic table group 16 element,
Examples include compounds of Group 2 elements of the periodic table and Group 16 elements of the periodic table, chalcogen spinels, and the like.

Specifically, the semiconductor nanoparticles are tin oxide (IV) (SnO ₂ ), tin sulfide (II, IV) (Sn (II) Sn) as a compound of a periodic table group 14 element and a periodic table group 16 element. (IV) S ₃ ), tin sulfide (IV) (SnS ₂ ), tin (II) sulfide (SnS), tin (II) selenide (SnSe), tin telluride (II) (SnTe), lead sulfide (PbS) ), Lead selenide (PbSe), lead telluride (PbTe), etc., as compounds of group 13 elements of the periodic table and group 15 elements of the periodic table, boron nitride (BN), boron phosphide (BP), boron arsenide (BAs), aluminum nitride (AlN), aluminum phosphide (AlP), aluminum arsenide (AlAs), aluminum antimonide (AlSb), gallium nitride (GaN), gallium phosphide (GaP), gallium arsenide ( aAs), gallium antimonide (GaSb), indium nitride (InN), indium phosphide (InP), indium arsenide (InAs), indium antimonide (InSb), etc. Periodic Table Group 13 Elements and Periodic Table Group 16 Elements As a compound, aluminum sulfide (Al ₂ S ₃ ), aluminum selenide (Al ₂ Se ₃ ), gallium sulfide (Ga ₂ S ₃ ), gallium selenide (Ge ₂ Se ₃ ), gallium telluride (Ga ₂ Te) ₃ ), indium oxide (In ₂ O ₃ ), indium sulfide (In ₂ S ₃ ), indium selenide (In ₂ Se ₃ ), indium telluride (In ₂ Te ₃ ), etc.
As a compound of a periodic table group 13 element and a periodic table group 17 element, thallium chloride (I) (TlCl), thallium bromide (I) (TlBr), thallium iodide (I) (TlI), etc. As compounds of Group 12 elements and Group 16 elements of the periodic table, zinc oxide (ZnO), zinc sulfide (ZnS), zinc selenide (ZnSe), zinc telluride (ZnTe), cadmium oxide (CdO), cadmium sulfide (CdS), cadmium selenide (CdSe), cadmium telluride (CdTe), mercury sulfide (HgS), mercury selenide (HgSe), mercury telluride (HgTe), etc. as the compounds of the group elements, antimony sulfide _{(III) (Sb 2 S 3} ), selenium antimony _{(III) (Sb 2 Se 3} ), antimony telluride (III _(Sb 2 _Te 3), bismuth sulfide _{(III) (Bi 2 S 3} ), bismuth selenide _{(III) (Bi 2 Se 3} ) and the like bismuth telluride _{(III) (Bi 2 Te 3} ), periodic table group 11 As a compound of an element and a group 16 element of the periodic table, copper (I) (Cu ₂ O), etc. As a compound of a group 11 element of the periodic table and a group 17 element of the periodic table, copper (I) (CuCl ), Copper (I) bromide (CuBr), copper (I) iodide (CuI), silver iodide (AgI), silver chloride (AgCl), silver bromide (AgBr), etc. As a compound with a group 16 element of the periodic table, as a compound with a group 16 element of the periodic table with a group 9 element of the periodic table, such as nickel (II) (NiO), cobalt (II) oxide (CoO), sulfide Cobalt (II) (CoS) and other Group 8 elements As a compound with group 16 element of the periodic table, as a compound of group 7 element of periodic table and group 16 element of periodic table, such as triiron tetroxide (Fe ₃ O ₄ ), iron (II) sulfide (FeS), As a compound of a periodic table group 6 element and a periodic table group 16 element, such as manganese oxide (II) (MnO), molybdenum sulfide (IV) (MoS ₂ ), tungsten oxide (IV) (WO ₂ ), etc. As a compound of Table Group 5 element and Periodic Group 16 element, vanadium oxide (II) (VO), vanadium oxide (II) (VO ₂ ), tantalum oxide (V) (Ta ₂ O ₅ ), etc. Periodic Table with Group 4 Elements As compounds with Group 16 elements, titanium oxide (TiO ₂ , Ti ₂ O ₅ , Ti ₂ O ₃ , Ti ₅ O _9, etc.), etc. Magnesium sulfide as a compound with Table 16 group elements Beam (MgS), magnesium selenide (MgSe), etc., as chalcogen spinels, cadmium oxide (II) chromium _{(III) (CdCr 2 O 4} ), cadmium selenide (II) chromium _{(III) (CdCr 2 Se 4} ) , Copper sulfide (II) chromium (III) (CuCr ₂ S ₄ ), mercury selenide (II) chromium (III) (HgCr ₂ Se ₄ ) and the like.

Among the above-described compounds, compounds mainly composed of Group 11-17 compound semiconductors such as AgI, Group 12-16 compound semiconductors such as CdSe, CdS, ZnS and ZnSe, and Group 13-15 compound semiconductors such as InAs and InP One of the semiconductors. In addition, the periodic table used by this invention shall follow the IUPAC inorganic chemical nomenclature 1990 rule.

  The particle diameter of the semiconductor nanoparticles of the present invention is preferably 10 nm or less, and particularly preferably 2 nm to 8 nm because the quantum effect and the like can be effectively utilized.

  Furthermore, since the semiconductor nanoparticles of the present invention can obtain visible light emission, the band gap energy of the compound semiconductor in the bulk state of the semiconductor composition constituting the semiconductor nanoparticles is 1.5 at a temperature of 300K. To 2.5 eV.

  Further, the phosphor 17 in the present invention may have a so-called core-shell structure including an inner core (core) and an outer shell (shell). The core-shell type semiconductor nanoparticles may be suitable for applications using an exciton absorption / emission band. In this case, it is generally effective to form an energy barrier by using a shell semiconductor particle having a forbidden band width (band gap) larger than that of the core. This is presumed to be due to a mechanism that suppresses the influence of an undesirable surface level or the like due to the influence of the outside world or crystal lattice defects on the crystal surface.

  The composition of the semiconductor material suitably used for the shell depends on the band gap of the core semiconductor crystal, but the band gap in the bulk state is 2.5 eV or more at a temperature of 300 K, such as BN, BAs, GaN, GaP, etc. III-V group compound semiconductors, II-VI group compound semiconductors such as ZnO and ZnS, and compounds of Group 2 elements of the periodic table and Group 16 elements of the periodic table such as MgS and MgSe are preferably used.

  Moreover, the phosphor 17 in the present invention may be covered with a surface modifying molecule made of an organic ligand. By covering the surface modification molecule, aggregation of the semiconductor nanoparticles can be suppressed and the function of the semiconductor nanoparticles can be expressed to the maximum. Surface modifying molecules are n-propyl, isopropyl, n-butyl, isobutyl, n-pentyl, cyclopentyl, n-hexyl, cyclohexyl, octyl, decyl, dodecyl, hexadecyl, octadecyl Examples thereof include hydrocarbon groups containing an aromatic hydrocarbon group such as an alkyl group having about 3 to 20 carbon atoms such as a group, phenyl group, benzyl group, naphthyl group, naphthylmethyl group, etc., among which n-hexyl group, octyl A linear alkyl group having about 6 to 16 carbon atoms such as a group, a decyl group, a dodecyl group, a hexadecyl group and the like is more preferable. Also, sulfur atom-containing functional groups such as mercapto group, disulfide group, thiophene ring, nitrogen atom-containing functional groups such as amino group, pyridine ring, amide bond, nitrile group, carboxyl group, sulfonic acid group, phosphonic acid group, phosphinic acid An acidic functional group such as a group, a phosphorus atom-containing functional group such as a phosphine group or a phosphine oxide group, or an oxygen atom-containing functional group such as a hydroxyl group, a carbonyl group, an ester bond, an ether bond, or a polyethylene glycol chain is preferred.

  The phosphor 17 in the present invention is manufactured by a general manufacturing method. Gas phase chemical reaction methods such as flame process, plasma process, electric heating process, laser process, physical cooling method, sol-gel method, alkoxide method, coprecipitation method, hot soap method, hydrothermal synthesis method, spray pyrolysis method, etc. A phase method, a mechanochemical bonding method, a microreactor method, a microwave heating method, and the like are used.

  The phosphor 17 included in the matrix layer 9 is not particularly limited as long as it is a material that emits light in the range of 400 to 900 nm. As the phosphor 17, a generally used phosphor can also be adopted.

For example, ZnS: Ag, ZnS: Ag, Al, ZnS: Ag, Cu, Ga, Cl, ZnS: Al + In ₂ O ₃ , ZnS: Zn + In ₂ O ₃ , (Ba, Eu) MgAl ₁₀ O ₁₇ , (Sr, Ca , Ba, Mg) ₁₀ (PO ₄ ) ₆ Cl ₁₇ : Eu, Sr ₁₀ (PO ₄ ) ₆ Cl ₁₂ : Eu, (Ba, Sr, Eu) (Mg, Mn) Al ₁₀ O ₁₇ , 10 (Sr, Ca , Ba, Eu) · 6PO ₄ · Cl ₂ , BaMg ₂ Al ₁₆ O ₂₅ : Eu, ZnS: Cl, Al, (Zn, Cd) S: Cu, Al, Y ₃ Al ₅ O ₁₂ : Tb, Y3 (Al , Ga) ₅ O ₁₂ : Tb, Y ₂ SiO ₅ : Tb, Zn ₂ SiO ₄ : Mn, ZnS: Cu + Zn ₂ SiO ₄ : Mn, Gd ₂ O ₂ S: Tb, (Zn, Cd) S: Ag, Y _{2 2 S: Tb, ZnS: Cu} , Al + In 2 O 3, (Zn, Cd) S: Ag + In 2 O 3, (Zn, Mn) 2 SiO 4, BaAl 12 O 19: Mn, (Ba, Sr, Mg) O AAl ₂ O ₃ : Mn, LaPO ₄ : Ce, Tb, 3 (Ba, Mg, Eu, Mn) O.8Al ₂ O ₃ , La ₂ O ₃ .0.2SiO ₂ .0.9P ₂ O ₅ : Ce , Tb, CeMgAl ₁₁ O ₁₉ : Tb, Y ₂ O ₂ S: Eu, Y ₂ O ₃ : Eu, Zn ₃ (PO ₄ ) ₂ : Mn, (Zn, Cd) S: Ag + In ₂ O ₃ , (Y, Gd, Eu) BO ₃ , (Y, Gd, Eu) ₂ O ₃ , YVO ₄ : Eu, La ₂ O ₂ S: Eu, Sm, YAG: Ce, and the like are used. The particle size is preferably 0.1 to 50 μm, particularly 1 μm to 20 μm in terms of the step of dispersing in the organic resin.

  Further, the phosphor 17 in the matrix layer 9 may be composed of a plurality of particles having different fluorescence spectra. The semiconductor composition may be different, or the same composition and the particle size may be different.

  In manufacturing the matrix layer 9, it is preferable that the phosphor 17 and the hygroscopic agent 15 described above are dispersed in a polymer resin.

  The polymer resin preferably has a structure that can easily disperse and carry the phosphor 17 and the hygroscopic agent 15 and can suppress the photodegradation of the phosphor. For example, epoxy resin, silicone resin, polyethylene terephthalate Polybutylene terephthalate, polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, cellulose acetate, polyarylate, vinyl acetate, polyvinyl alcohol, and derivatives of these materials are used.

  In particular, it is preferable to have a light transmittance of 95% or more in a wavelength region of 350 nm or more. In addition to such light transmittance, a silicone resin is more preferably used from the viewpoint of heat resistance. In the case of a silicone resin, it is not particularly limited whether it is linear or has a crosslinked structure. Substituents on silicon are methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, n-pentyl group, cyclopentyl group, n-hexyl group, cyclohexyl group, octyl group, Hydrocarbon groups containing aromatic hydrocarbon groups such as alkyl groups having about 1 to 20 carbon atoms such as decyl group, dodecyl group, hexadecyl group, octadecyl group, phenyl group, benzyl group, naphthyl group, naphthylmethyl group, etc. Among them, a linear alkyl group having a small number of carbon atoms such as a methyl group and an ethyl group is preferable.

  The thickness of the matrix layer 9 of the present invention is preferably 0.5 to 10 mm, particularly 1.0 to 5 mm, from the viewpoints of conversion efficiency and ultraviolet and visible light transmittance in each matrix layer. Within this range, the excitation light emitted from the light emitting element can be converted into output light with high efficiency, and the converted output light can be transmitted outside with high efficiency.

  The light emitting element 7 preferably emits light having a center wavelength of 450 nm or less, particularly 380 to 420 nm. By using excitation light in the wavelength range of this range, the phosphor can be excited efficiently, the intensity of output light can be increased, and a light emitting device with higher emission intensity can be obtained.

  Below, the manufacturing method of the light-emitting device of this invention is illustrated.

  First, if necessary, the phosphor 17 and the hygroscopic agent 15 and the raw material of the uncured resin 13 are dispersed and mixed to produce a paste.

  For example, as shown in FIG. 1, when the light emitting device 1 having a form in which the light emitting element 7 is directly covered with the matrix layer 9 is formed, the light emitting element 7 is covered with the substrate 3 on which the light emitting element 7 is mounted. The paste is disposed on the surface.

  Thereafter, the paste is cured by heating at 150 to 250 ° C. for 0.5 to 4 hours to form the matrix layer 9.

  For example, as shown in FIG. 3, when the light emitting device 1 is formed in such a manner that the light emitting element 7 is directly covered with the matrix layer 9 and the matrix layer 9 has two or more layers, the light emitting element 7 is mounted. A paste is disposed on the substrate 3 so as to cover the light emitting element 7, and a paste in which the content of the phosphor 17 and the hygroscopic agent 15 is changed is disposed so as to cover the paste covering the light emitting element 7. Thereafter, heating is performed at 150 to 250 ° C. for 0.5 to 4 hours, the paste is cured, the paste is cured, and two or more matrix layers 9 are formed.

  As another manufacturing method, a sheet produced by tape-molding a paste by a molding method capable of forming a sheet such as a doctor blade method, a die coater method, an extrusion method, a spin coating method, or a dip method so that the light emitting element 7 is covered. It may be arranged.

  Alternatively, a plurality of sheets in which the phosphor 17 and the hygroscopic agent 15 are dispersed may be laminated in a B-stage state, and further thermocompression bonded at a temperature lower than the curing temperature, and the sheet may be disposed so as to cover the light emitting element 7. Good.

  Further, a moisture-proof layer 19 made of glass or ceramic can be disposed so as to cover the matrix layer 9.

  In the manufacturing method described above, the addition amount of the phosphor 17 and the hygroscopic agent 15 is appropriately changed with respect to the raw material of the resin 13, and the paste, tape, and conversely the phosphor 17 having a large amount of the phosphor 17 and a small amount of the hygroscopic agent 15. The distribution of the phosphor 17 and the hygroscopic agent 15 can be easily realized by using a paste and a tape with a small amount of the hygroscopic agent 15 and using two or more layers of these pastes and tapes.

  Furthermore, in the light-emitting device of the present invention, the moisture-proof layer 19 has a moisture permeability lower than that of the matrix layer 9 and has a function of suppressing moisture from reaching the matrix layer 9 and the light-emitting element 7.

In order to ensure high reliability, the moisture-proof layer 19 preferably has a moisture permeability of 1 g / m ² · day or less, particularly 0.5 g / m ² · day or less, and further 0.3 g. By setting it to / m ² · day or less, the characteristic deterioration of the light-emitting device can be remarkably suppressed. The moisture permeability can be measured based on the cup method described in JIS K 0208, for example.

  Further, it is desirable that the moisture-proof layer 19 has a thickness of 1 μm or more, particularly 100 μm or more, and more preferably 200 μm or more in order to suppress variations in moisture-proof ability due to defects and thickness variations. Further, even if the moisture-proof layer 19 having translucency is used, it is difficult to completely prevent the moisture-proof layer 19 from absorbing light. The thickness of the layer 19 is preferably 1000 μm or less, particularly preferably 500 μm or less, and more preferably 200 μm or less.

  As described above, the material constituting the moisture-proof layer 19 described above is essential to be a material having lower hygroscopicity than the matrix layer 9, but additionally has a high moisture permeation preventing ability and a high heat resistance. Since it is desirable that the difference in coefficient of thermal expansion between the LED chip and the package is small, the use of one type selected from the group consisting of a composite material of glass and ceramics, glass, ceramics, and single crystal provides the above-mentioned characteristics. The moisture-proof layer 19 can be easily formed.

For example, the glass composition used in the moisture-proof layer _19, SiO 2 _{-CaO-MgO-based, SiO 2 -BaO-Al 2 O} 3 _based, SiO 2 _-B 2 _{O 3 based,} SiO 2 _-B 2 _{O 3} -Al ₂ O _{3 system,} SiO 2 _-Al 2 _{O 3} - alkali metal oxide, more alkali metal oxides in these systems, ZnO, PbO, _Pb, composition containing ZrO 2, TiO ₂ or the like The moisture-proof layer 19 can be produced by, for example, a method in which these glass compositions are melted or softened, then formed into a sheet shape, and a sheet is formed and bonded.

Examples of the ceramic used as the moisture-proof layer 19 include Al ₂ O ₃ , SiO ₂ , Y ₂ O ₃ , MgO, CaO, BeO, ZrO ₂ , HfO ₂ , ThO ₂ , which are known as translucent ceramics. It is preferable to include at least one selected from Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , and MgAlO ₄ . When these ceramics having excellent water permeation preventing ability and translucency are used, deterioration of characteristics due to moisture is suppressed, and light emitted from the matrix layer 9 can be efficiently extracted to the outside.

  For the moisture-proof layer 19 using such ceramics, a uniform and strong film can be formed in one step by, for example, a CVD method in which a ceramic film is directly formed on the surface of the matrix layer 9. Further, after the ceramic film is formed on another substrate by the CVD method, the substrate can be removed and the ceramic film can be adhered to the matrix layer 9. This method can easily form a film even with a material that requires a high temperature and a special atmosphere to form the film. Further, it is possible to obtain a ceramic film by a method in which a raw material is mixed with a binder resin and then formed into a sheet shape by a doctor blade, a mechanical press or the like and sintered.

  Further, the moisture-proof layer 19 may be formed by mixing the glass and the ceramic with a binder using a ball mill or the like and then forming the sheet and baking it.

  First, an electrode 5 mainly composed of W was formed, and a light emitting element 7 was mounted on an alumina substrate 3 provided with a reflector 11 through bumps 6.

Next, a matrix layer 9 having the composition shown in Table 1 was disposed so as to cover the light emitting element 7 and the electrode 5.

  A thermosetting silicone resin X-35-140 manufactured by Shin-Etsu Silicone Co., Ltd. was used as the resin 13 for the matrix layer 9. As the phosphor 17, CdSe having a particle diameter of about 3 nm was used as nanosemiconductor particles. In addition, CdSe used what was produced in the laboratory by the hot soap method. Silica gel, which is a commercially available reagent, was used as the hygroscopic agent 15, and Zeolum A-3 manufactured by Tosoh Corporation was used as the zeolite. Since the moisture absorbent 15 has a large particle size as it is, it was pulverized in a toluene solvent using a bead mill. The average particle size after pulverization was about 0.3 μm.

  The humectant 15 after pulverization was heat-treated at 300 ° C. for 5 hours to remove moisture absorbed in the process from the hygroscopic material 15.

  Silicone resin 13, phosphor 17 and hygroscopic agent 15 were mixed and dispersed to obtain a paste. This paste was molded by a doctor blade method to produce a tape having a thickness of 200 μm. When molding, heat was heated at 50 to 80 ° C. for 5 to 60 minutes to set the cured state of the sheet to the B stage.

Table 1 shows the composition of the produced sheet. Each sheet was produced by changing the type and filling amount of the filler. Sheet No. The silica used in 1-4 was Admafine SOC-2 silica having an average particle size of 0.5 μm. Sheet No. Nos. 5 to 12 used commercially available silica gels having specific surface areas of 40 m ² / g and 50 m ² / g. Sheet No. 13-20 specific surface area using the above zeolite ^{40 m} 2 / g and ^{50 m} 2 / g.

In the combinations shown in Table 2, the first layer on the light emitting element 7 side is formed by potting, and the second to fourth layers are formed by stacking three sheets prepared in advance. Laminated on top.

  As a reliability test, these samples were left in a high-temperature and high-humidity environment with a temperature of 85 ° C. and a relative humidity of 85%, and electrical failures were confirmed with the elapsed time shown in Table 2.

  Although no initial failure occurred in any of the samples, Sample No. using silica having no hygroscopicity. In 1, the failure occurred early. In Samples 2 and 3 using a hygroscopic filler, no defect occurred even after 1000 hours.

  Further, by combining four sheets shown in Table 1 in the combinations shown in Table 3, samples having a large amount of hygroscopic agent on the surface side of the matrix layer 9, a sample having a small amount, and the like are produced. The sample was left in a high-temperature and high-humidity environment with a relative humidity of 85%, and the initial emission intensity, the emission intensity after 1000 hours in an environment of 85 ° C. and 85RH%, and the rate of decrease in the emission intensity were measured at the elapsed time shown in Table 3.

The emission intensity was measured using an integrating sphere (total luminous flux measurement system: DAS-2100) manufactured by Labsphere. The difference in the initial emission intensity of each sample is due to the influence of the filling amount of the phosphor.

As shown in Table 3, when compared with silica gel and zeolite, zeolite gave better results. Further, the hygroscopic agent having a specific surface area of 50 m ² / g has better performance than the specific surface area of 40 m ² / g, and both silica gel and zeolite have a specific surface area of 50 m ² / g or more and a reduction rate of less than 10%. Sample No. Samples with more phosphors on the surface side and fewer hygroscopic agents as shown in 6 and 7 have a large decrease in emission intensity and do not satisfy performance. On the surface side, the more hygroscopic agent and the less phosphor, the more the opposite phosphor and the better the performance than the sample with less hygroscopic agent. Moisture around the phosphor leads to performance degradation.

Next, the effect of the moisture-proof layer was tested.

  As shown in Table 4, sample no. No. 10 was reduced by 10% or more in the reliability test. Sample No. 11 was less than 10% from the layer structure.

As the moisture-proof layer, optical SiO ₂ —BaO—Al ₂ O ₃ glass (sample No. 12) and Al ₂ O ₃ ceramic (sample No. 13) were used. Since glass and ceramic do not allow moisture to penetrate at all, only residual moisture contributes to performance degradation. As shown in Table 4, a very high performance can be maintained by providing a moisture-proof layer.

It is sectional drawing explaining the light-emitting device of this invention. It is sectional drawing explaining the light-emitting device of this invention. It is sectional drawing explaining the light-emitting device of this invention. It is sectional drawing explaining the light-emitting device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light-emitting device 3 ... Board | substrate 5 ... Electrode 6 ... Bump 7 ... Light-emitting element 9 ... Matrix layer 11 ... Reflector 13 ... Resin 15 ... Filler 17 ... Phosphor 19 ... Hygroscopic layer

Claims (13)

A light-emitting device including a light-emitting element that emits excitation light disposed on a substrate and a matrix layer mainly composed of a resin formed to cover the light-emitting element, the matrix layer being non-fluorescent A light-emitting device characterized by containing a hygroscopic agent. The light emitting device according to claim 1, wherein a phosphor that converts excitation light into visible light is dispersed in the matrix layer. The light emitting device according to claim 2, wherein the phosphor is a semiconductor nanoparticle. The light-emitting device according to claim 1, wherein the moisture absorbent has a high content on the surface side of the matrix layer. The light emitting device according to any one of claims 2 to 4, wherein the phosphor has a low content on the surface side of the matrix layer. The light-emitting device according to claim 1, wherein the hygroscopic agent is silica gel. The light-emitting device according to claim 1, wherein the hygroscopic agent is zeolite. 8. The light-emitting device according to claim 1, wherein the hygroscopic agent has a BET specific surface area of 50 m ² / g or more. The light emitting device according to claim 1, wherein the resin contains a silicone resin. The light-emitting device according to claim 1, wherein a moisture-proof layer having a lower water absorption rate than the matrix layer is formed so as to cover the matrix layer. The light-emitting device according to claim 10, wherein the moisture permeability of the moisture-proof layer is 1 g / m ² · day or less. The light emitting device according to claim 10 or 11, wherein the moisture-proof layer has a thickness of 1 to 1000 µm. The light-emitting device according to claim 10, wherein the moisture-proof layer is made of one selected from the group consisting of a glass / ceramic composite material, glass, ceramics, and a single crystal.

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