JP2012079883A - Led light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED light emitting device excellent in moisture resistance of a phosphor, thus hardly causing decrease in luminous intensity even under a high-temperature and high-humidity environment.SOLUTION: An LED light emitting device includes: an LED chip; a resin frame surrounding the LED chip; and a phosphor layer filled in a recessed part formed by the resin frame. The phosphor layer contains a phosphor and a sealing resin. The phosphor has a phosphor parent body 1, an intermediate layer 2 and a surface layer 3, toward an outermost surface, and has a molar ratio of an alkali earth metal to silicon of 1.5 or more. In addition, the LED light emitting device has a luminous intensity retention of 90% or more after electric conduction for 1,000 hours at the conditions where temperature is 60 to 90°C, relative humidity is 60 to 90%, and current is 20 to 120 mA.

Description

The present invention relates to an LED light emitting device.

In recent years, a semiconductor light emitting element (white LED) that emits white light has attracted attention as a next-generation light source because it has advantages such as low power consumption, high efficiency, environmental friendliness, and long life.
As a method for producing white light in a white LED, a method of combining a blue or ultraviolet LED and a phosphor (red, yellow, green phosphor, etc.) that can be excited by the light is generally used.

In addition, silicate (also called silicate) phosphors having alkaline earth metal elements are attracting attention because they have characteristics such as easy emission of a wide range of emission wavelengths by composition adjustment and high emission efficiency. Yes. As examples of such silicate phosphors, for example, green phosphors described in Patent Document 1, orange phosphors described in Patent Document 2, and yellow phosphors described in Patent Document 3 are given as representative examples. It is done.

However, the silicate phosphor having such an alkaline earth metal element has a problem that its surface is easily decomposed and deteriorated by water vapor or moisture in the air. For this reason, when used for a long time in the atmosphere, the emission intensity and the color tone are liable to decrease, the characteristics as a phosphor are lowered, and there is a serious problem in durability.
On the other hand, as a method of improving the moisture resistance of the phosphor, there is a method of coating the surface of the phosphor particles with an oxide or the like using a gas phase method (dry method), a liquid phase method (wet method) or the like. It is being considered.
For example, as a method by a vapor phase method, aluminum oxide is formed on the surface of sulfide phosphor particles by a method using chemical vapor deposition (CVD) (Patent Document 4) or a method using plasma method (Patent Document 5). A method for coating a membrane is disclosed.

Examples of the liquid phase method include a sol-gel reaction method and a neutralization precipitation method. For example, Patent Document 6 discloses an alkoxide such as Si and Ti and / or a derivative thereof at a reaction temperature of 0 to 20 ° C. A surface treatment method for phosphor particles by hydrolysis and dehydration polymerization in the presence of a large amount of ammonia water is disclosed.
Furthermore, Patent Document 7 discloses a method for coating a zirconia film using a sol-gel reaction method. Patent Document 8 discloses a method in which an ion-containing acidic solution such as aluminum is added to an alkaline solution in which a phosphor is dispersed, and a metal hydroxide is precipitated on the surface of the phosphor particles by a neutralization reaction. Yes.

However, in the vapor phase methods disclosed in Patent Documents 4 and 5, it is difficult to completely disperse the fine particles of the phosphor particles, so that the surface of each of the phosphor particles is uniform and even on the entire surface. There is a problem that it is practically difficult to coat and pinholes, coating variations, and the like are likely to occur. In addition, since the vapor phase method is usually performed at a high temperature of 400 ° C. or higher, there is a problem that the fluorescence characteristics are remarkably deteriorated after the treatment depending on the kind of the phosphor. Furthermore, since the apparatus is large, the manufacturing cost is high.

On the other hand, when the sol-gel reaction method, which is a liquid phase method, is used (Patent Documents 6 and 7), the degree of freedom in selecting the type of coating is large, but the metal alkoxide as a starting material is usually highly reactive, and phosphor particles It was very difficult to control the reaction conditions for causing the hydrolysis reaction only on the surface. In addition, the film obtained by the sol-gel reaction method contains organic components such as an alkoxyl group left behind due to incomplete hydrolysis and alcohol removed by the hydrolysis reaction. It was difficult.
Furthermore, in the coating method disclosed in Patent Document 6, since the hydrolysis reaction is performed in the presence of a large amount of aqueous ammonia, most of the raw material is reacted and consumed in a solution other than the surface of the phosphor particles, resulting in reaction efficiency and cost. There was also a problem. In addition, since a large amount of aqueous ammonia is contained, the phosphor may be degraded by hydrolysis during the treatment process.
The method disclosed in Patent Document 7 requires a long-time reaction and precise temperature and process control, and has a problem in efficiency and cost.
On the other hand, in the neutralization precipitation method disclosed in Patent Document 8, it was practically difficult to deposit the coating as a continuous film on the surface of the phosphor particles.
Thus, the conventional phosphor has a big problem in terms of moisture resistance, etc., when such a phosphor is used in an LED light emitting device, especially when used for a long time in a hot and humid environment, There was a problem that the luminous intensity was greatly reduced.

Special table 2009-515030 JP 2007-131843 A JP 2007-186664 A JP 2001-139951 A Special table 2009-524736 gazette JP 2008-1111080 A JP 2009-132902 A JP-A-11-256150

An object of the present invention is to provide an LED light-emitting device in which the luminous intensity is hardly lowered even in a high-temperature and high-humidity environment because the phosphor has excellent moisture resistance.

The present invention is an LED light emitting device comprising an LED chip, a resin frame surrounding the LED chip, and a phosphor layer filled in a recess formed by the resin frame, wherein the phosphor layer is sealed with the phosphor. The phosphor has a phosphor matrix, an intermediate layer, and a surface layer toward the outermost surface, the molar ratio of the alkaline earth metal to silicon is 1.5 or more, and The LED light-emitting device is an LED light-emitting device having a luminous intensity retention of 90% or more after being energized for 1000 hours under conditions of a temperature of 60 to 90 ° C., a relative humidity of 60 to 90%, and a current of 20 to 120 mA.
The present invention is described in detail below.

As a result of intensive studies, the present inventors have, as a phosphor used in the LED light-emitting device, a phosphor matrix, an intermediate layer, and a surface layer toward the outermost surface, and an alkaline earth metal with respect to silicon. It has been found that by using a phosphor having a molar ratio within a predetermined range, it is possible to significantly improve the moisture resistance without deteriorating the fluorescence characteristics and to obtain a phosphor having high dispersibility. The present invention has been completed.

The LED light emitting device of the present invention has a luminous intensity retention ratio of 90% or more after energization for 1000 hours under the conditions of a temperature of 60 to 90 ° C., a relative humidity of 60 to 90%, and a current of 20 to 120 mA.
In particular, the luminous intensity retention after energization for 1000 hours under the conditions of a temperature of 85 ° C., a relative humidity of 85%, and a current of 20 mA is 90% or more.
If the luminous intensity retention is less than 90%, the light emission intensity tends to decrease with time during actual use, and the durability may be insufficient. The luminous intensity retention is preferably 95% or more.
The luminous intensity retention ratio represents the ratio of luminous intensity before and after energization under the above-mentioned conditions [(luminous intensity after energization / luminance before energization) × 100], and the luminous intensity is, for example, OL770 manufactured by Optronic Laboratories. It can be measured using a measurement system.

FIG. 1 shows an embodiment of the LED light emitting device of the present invention. In addition, the LED light-emitting device of this invention is not limited to a package cup type as shown in FIG. 1, It can change suitably.

The LED light-emitting device of the present invention includes an LED chip 103 installed on a substrate (support) 100, a resin frame 104 having a cup-shaped recess 107 whose upper opening is wider than the bottom, and fluorescence filled in the recess. It has a body layer 110. Hereinafter, each part is explained in full detail.

(1) The LED chip 103 is mounted with Ag paste or the like at the center of the substantially circular bottom surface of the LED chip recess 107.
The LED chip 103 only needs to emit light that can excite the phosphor. Usually, those that emit light having a wavelength from the near ultraviolet region to the blue region are used, and among them, a GaN-based LED using a GaN-based compound semiconductor is preferable. The GaN-based LED has a remarkably large light emission output and external quantum efficiency, and can be combined with the phosphor to obtain very bright light emission with very low power. The GaN-based LED preferably has an Al _x Ga _y N light emitting layer, a GaN light emitting layer, or an In _x Ga _y N light emitting layer. Among the GaN-based LEDs, those having an In _x Ga _y N light emitting layer are particularly preferable because the light emission intensity is very strong. In the above, the value of x + y is usually in the range of 0.8 to 1.2. In the GaN-based LED, those in which the light emitting layer is doped with Zn or Si or those without a dopant are preferable for adjusting the light emission characteristics.
The GaN-based LED has these light emitting layer, p layer, n layer, electrode and substrate as basic components, and the light emitting layer is made of n-type and p-type Al _x Ga _y N layers, GaN layers, or In _x. Those having a hetero structure sandwiched with a Ga _y N layer or the like have high luminous efficiency, and those having a hetero structure having a quantum well structure have higher luminous efficiency and are more preferable.

The electrodes (not shown) of the LED chip 103 are connected to the leads 101 and 102 by bonding wires 105 and 106 made of Au or the like, respectively. The arrangement of the leads 101 and 102 can be changed as appropriate.
As the LED chip 103, a flip chip type having an n-type electrode and a p-type electrode on the same plane can be used. In this case, problems caused by the wire such as wire breakage and peeling and light absorption by the wire are solved, and a highly reliable and high-luminance semiconductor light-emitting device can be obtained. In addition, an n-type substrate may be used for the LED chip 103 to have the following configuration. Specifically, an n-type electrode is formed on the back surface of the n-type substrate, a p-type electrode is formed on the upper surface of the semiconductor layer on the substrate, and the n-type electrode or the p-type electrode is mounted on a lead. The p-type electrode or the n-type electrode can be connected to the other lead by a wire. The size of the LED chip 103 and the size and shape of the recess 107 can be changed as appropriate.

(2) Resin frame The resin frame 104 is for holding the LED chip 103 and the phosphor layer 110. A cup-shaped recess 107 is formed on the upper surface of the resin frame 104 so that the light emitted from the LED light emitting device can have directivity, and the emitted light can be used effectively. Furthermore, the inner surface 111 of the concave portion of the resin frame 104 has a high reflectance of light in the entire visible light region by metal plating such as silver, so that the light hitting the inner surface of the concave portion of the frame is also emitted from the light emitting device. It can discharge in a predetermined direction.

An LED chip 103 is installed on the bottom of the recess 107 of the resin frame 104. The resin frame 104 and the LED chip 103 are bonded by a silver paste (a mixture of silver particles in an adhesive). This silver paste also plays a role of efficiently radiating the heat generated in the LED chip 103 to the resin frame 104.
Further, gold wires 106 and 105 for supplying power to the LED chip 103 are attached to the resin frame 104. The gold wire is connected by wire bonding, and when the wire is energized, power is supplied to the LED chip 103 and light is emitted from the LED chip 103.

(3) The phosphor layer 110 is filled in the recess 107 of the phosphor layer resin frame 104. The phosphor layer 110 can be formed by dispersing or precipitating a predetermined proportion of the phosphor 108 in the sealing resin 109.

(3-1) Phosphor When the LED light emitting device of the present invention is configured as a white light emitting device, one or more phosphors may be appropriately combined so as to obtain desired white light. When a blue light emitting element is used as a light source, it is preferable to use a yellow phosphor having a complementary color relationship of blue as a phosphor, and red and green phosphors to obtain white with higher color rendering properties. When using a semiconductor light emitting device that emits near-ultraviolet light, phosphors of three colors of red, green, and blue are preferably used.
Specifically, in the case where the LED light-emitting device of the present invention is configured as a white light-emitting device, examples of preferable combinations of a light source and a phosphor include the following combinations (i) to (iii). .
(I) A blue light emitter (blue LED or the like) is used as a light source, and a red phosphor and a green phosphor are used as phosphors.
(Ii) A near ultraviolet light emitter (near ultraviolet LED or the like) is used as a light source, and a red phosphor, a green phosphor and a blue phosphor are used in combination as phosphors.
(Iii) A blue light emitter (blue LED or the like) is used as a light source, and an orange phosphor and a green phosphor are used.

The phosphor of the present invention has a phosphor matrix, an intermediate layer, and a surface layer toward the outermost surface.
FIG. 2 schematically shows a cross section of the phosphor.
As shown in FIG. 2, an intermediate layer 2 is formed on the outer surface of the phosphor matrix 1, and a surface layer 3 is formed on the outer surface of the intermediate layer 2.

The phosphor contains silicon and an alkaline earth metal.
By containing such an element, the luminance and stability of the phosphor are improved, and at the same time, the emission wavelength can be easily adjusted. The alkaline earth metal refers to an element belonging to Group 2 of the periodic table, such as beryllium, magnesium, calcium, strontium, barium, and radium.
Especially, it is preferable that the said fluorescent substance contains the silicate which has the said alkaline-earth metal.

Examples of the silicates having an alkaline earth metal include, for example, a matrix crystal structure that is substantially the same as the crystal structure of M ₂ SiO ₄ or M ₃ SiO ₅ (where M is Mg, Ca, Sr, and Ba). And at least one selected from the group consisting of Fe, Mn, Cr, Bi, Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm And a phosphor containing at least one selected from the group consisting of Yb.
The silicate having the alkaline earth metal may contain an appropriate amount of, for example, Zn, Ga, Al, Y, Gd, Tb and the like. The phosphor may contain an appropriate amount of a small amount of a halogen element (for example, F, Cl, Br), sulfur (S), or phosphorus (P).

The phosphor has a molar ratio of alkaline earth metal to silicon of 1.5 or more.
When the molar ratio is less than 1.5, the crystal structure becomes unstable, and it becomes difficult to obtain stable fluorescence characteristics. Preferably it is 1.7 or more.

Towards the outermost surface, the phosphor having a phosphor matrix, an intermediate layer, and a surface layer, and having a molar ratio of alkaline earth metal to silicon of 1.5 or more, for example, toward the outermost surface, At least one selected from a phosphor matrix containing an alkaline earth metal, an intermediate layer containing an alkaline earth metal, an alkaline earth metal, and elements of Groups 4 to 6 of the periodic table, yttrium and silicon And a phosphor satisfying the following formulas (1) and (2) in which the content of alkaline earth metal in the phosphor matrix, the intermediate layer and the surface layer is preferable.

In the formula, C ₁ represents the content of alkaline earth metal in the phosphor matrix, C ₂ represents the content of alkaline earth metal in the intermediate layer, and C ₃ represents the content of alkaline earth metal in the surface layer.

C ₂ is preferably 2/3 or less of C ₁ . As a result, the intermediate layer 2 is substantially rich in Si and O, and the moisture resistance of the phosphor is improved. If it exceeds 2/3, the moisture resistance may be insufficient. It is more preferable that it is 1/3 or less.

In the present invention, the content of the alkaline earth metal is represented by the content (% by weight) of the alkaline earth metal with respect to all elements constituting the phosphor matrix, the intermediate layer, or the surface layer.
The content of alkaline earth metal in each of the above layers can be measured by using an energy dispersive X-ray spectrometer (EDX) attached to a field emission transmission electron microscope (Energy-Dispersive X-ray Spectrometer, EDX). it can.

The phosphor matrix used for the phosphor contains an alkaline earth metal. Examples of the phosphor matrix having such an alkaline earth metal include sulfides, aluminates, nitrides, oxynitrides, phosphates, halon phosphates, and silicates.
Among these, the phosphor matrix preferably contains a silicate having an alkaline earth metal element.

Examples of the phosphor matrix include, for example, a phosphor matrix having a structure as shown in the following formula (3), a phosphor matrix having a structure as shown in the following formula (4), and a structure as shown in the following formula (5). And a phosphor matrix having

In formula (3), M is at least one selected from the group consisting of Mg, Ca, Ba, and Zn, and x and y are 0 ≦ x ≦ 0.5, 2.6 ≦ y ≦ 3.3, respectively. Is within the range.

In Formula (4), L1 is at least one selected from the group consisting of Mg, Ca, Ba and Zn, and L2 is at least selected from the group consisting of B, Al, Ga, C, Ge, N and P. L3 is at least one selected from the group consisting of F, Cl, Br, N and S, and x is 1.5 to 2.5.

In formula (5), M1 and M2 are at least one selected from the group consisting of Mg, Ca, Ba, and Zn, and a, x, y, z, and u are each 0.6 ≦ a ≦ 0.85. 0.3 ≦ x ≦ 0.6, 0.85 ≦ y ≦ 1, 1.5 ≦ z ≦ 2.5, 2.6 ≦ u ≦ 3.3.

Specific examples of the phosphor matrix include, for example, Sr ₃ SiO ₅ : Eu ²⁺ , (Sr _0.9 Mg _0.025 Ba _0.075 ) ₃ SiO ₅ : Eu ²⁺ , (Sr _0.9 Mg _0.05 Ba _0.05 ) _2.7 SiO ₅ : Orange phosphor mainly composed of Eu ²⁺ , (Sr _0.6 Ba _0.4 ) ₂ SiO ₄ : Eu ²⁺ F ⁻ , (Sr _0.7 Ba _{0. 3} ) ₂ SiO ₄ : Eu ²⁺ F ⁻ , (Ba, Sr, Ca) ₂ (Mg, Zn) Si ₂ O ₇ : Eu ²⁺ or the like as a main component, a green phosphor, 0.72 [(Sr _1.025 Ba _0.925 Mg _0.05 ) Si _1.03 O ₄ Eu _0.05 F _0.12 ] · 0.28 [Sr ₃ Si _1.02 O ₅ Eu _0.6 F _0.13 ] yellow phosphor and, _and, Ba 2 MgSi ₂ O ^{_{: Eu 2+, Ba 2 ZnSi 2}} O 7: blue phosphor can be cited as a main component ^{Eu 2+} and the like.

No particular limitation is imposed on the particle size of the phosphor matrix, the central particle size _{(D 50)} preferably in a normally 0.1~100μm range, more preferably 1.0～50Myuemu, more preferably 2. 0 to 30 μm. When the D ₅₀ is too small, not only the luminance decreases, phosphor matrix itself is agglutination reagent, uniform coating processing becomes difficult. Further, when D ₅₀ is too large, dispersibility becomes poor in the resin, which may adversely affect the characteristics of the light emitting device.

The intermediate layer is characterized by containing an alkaline earth metal and having a lower alkaline earth metal content than the phosphor matrix and the surface layer. Thus, low content of alkaline earth metal means that content of metals other than alkaline earth metal is high. For example, when the surface of a phosphor matrix having a structure such as M ₂ SiO ₄ or M ₃ SiO ₅ is chemically modified to form a surface layer and an intermediate layer, the content of the alkaline earth metal in the intermediate layer is The alkaline earth metal content in the phosphor matrix becomes lower, and as a result, the alkaline earth metal is deficient in the intermediate layer, and the Si and O contents are high.

By forming such an intermediate layer, it is possible to prevent the phosphor from being deteriorated by water in the coating process. In general, when processing a phosphor having poor moisture resistance, it is necessary to avoid the use of an aqueous solution. For example, in the case of a phosphor made of silicate, decoloration deterioration often occurs within several minutes in pure water. For this reason, when the surface treatment is performed by a wet method such as a sol-gel reaction method, it is almost always performed in an organic solvent such as alcohol.
On the other hand, in this invention, even when it coat | covers in 100% of aqueous solution, the decoloring deterioration of the fluorescent substance by water is not seen. The reason for this is not necessarily clear, but it is considered that the intermediate layer having a low alkaline earth metal content was formed earlier in the early stage of the coating process, so that deterioration due to water during the coating process was suppressed. . In addition, the fact that the coating treatment can be performed in an aqueous solution not only eliminates problems such as waste liquid treatment when using an organic solvent, but also leads to cost reduction.
Furthermore, by forming the intermediate layer having a low content of the alkaline earth metal, the stability to water is increased, and the moisture resistance during use of the phosphor can be improved.

The preferable lower limit of the content of alkaline earth metal in the intermediate layer is 0.01% by weight, and the preferable upper limit is 40% by weight. If the content of the alkaline earth metal in the intermediate layer is out of the above range, the phosphor may be decomposed and degraded by water during the coating process.

The intermediate layer may contain fluorine in addition to the alkaline earth metal.
The total content of fluorine and alkaline earth metal in the intermediate layer is preferably 40% by weight or less. When the total content of fluorine and alkaline earth metal exceeds 40% by weight, the silicon and oxygen contents are relatively lowered, and the moisture resistance of the phosphor is lowered.
In addition, the presence of fluorine in the intermediate layer allows a fluoride to be formed between the fluorine and the alkaline earth metal. Alkaline earth metal fluorides are insoluble in water and are more water resistant than silicates of the same metal type.

The thickness of the said intermediate | middle layer is not specifically limited, Usually, it is preferable that it is 0.5-2000 nm. More preferably, it is 1-1000 nm, More preferably, it is 2-500 nm. If the thickness of the intermediate layer is too thin, the above-described effect of preventing deterioration due to water becomes insufficient, and if it is too thick, the fluorescent properties of the phosphor may be adversely affected.

The surface layer contains at least one selected from elements of Groups 4 to 6 of the periodic table, yttrium and silicon.

Although the existence form of at least one selected from the elements of Groups 4 to 6 of the periodic table, yttrium and silicon in the surface layer is not clear, it is preferably a fluoride, an oxide or a double oxide. In particular, an oxide is preferable. Further, a double oxide (for example, barium titanate (BaTiO ₃ )) or the like may be formed.
Since the fluoride, oxide, or double oxide has high moisture resistance, moisture resistance is further improved by forming the surface layer. In particular, since oxides such as Ti, Zr, and silicon have high water resistance, the higher the content of such a metal in the surface layer, the better.

A preferable lower limit of the content of at least one selected from Group 4 to 6 elements of the periodic table, yttrium and silicon in the surface layer is 30% by weight. When the content is 30% by weight or more, the surface layer is substantially composed mainly of at least one selected from elements of Groups 4 to 6 of the periodic table, yttrium and silicon, Moisture resistance is improved. For example, when the alkaline earth metal contained in the surface layer is Ba (70 wt%) and the metal other than the alkaline earth metal is Ti (30 wt%), the composition ratio (molar ratio) of Ti and Ba Is converted to Ti, the number of Ti is about three times that of Ba.

When the surface layer contains an alkaline earth metal, it is preferably an alkaline earth metal derived from the phosphor matrix. Here, “being derived from the phosphor host material” means that a part (usually the outermost surface) of the phosphor host crystal is modified by chemical treatment, resulting in a structure or composition different from the host crystal structure or composition of the phosphor. Means that.

The thickness of the said surface layer is not specifically limited, Usually, it is preferable that it is 0.5-2000 nm. More preferably, it is 1.0-1000 nm, More preferably, it is 2.0-500 nm. If the thickness of the surface layer is too thin, the effect of preventing deterioration is insufficient, and if it is too thick, the fluorescent properties of the phosphor may be adversely affected.

(Method for forming intermediate layer and surface layer)
The intermediate layer and the surface layer disperse the phosphor matrix in a solution containing MF ₆ ^2- complex ions (M is at least one selected from Group 4 to 6 elements of the periodic table, yttrium and silicon), It is preferable to use a method having a step of forming an intermediate layer and a surface layer by contacting them. Usually, when forming a multilayer, it is necessary to carry out a layer forming step by dividing several steps. However, in the present invention, there is no need for a complicated step as in the prior art. It can be realized in one process with the same processing solution.

The mechanism by which the intermediate layer and the surface layer are formed by using the phosphor manufacturing method is not necessarily clear, but is thought to be formed through the following three processes.
1) Elution of alkaline earth metal from the outermost surface layer of the phosphor matrix;
2) The eluted alkaline earth metal ions react with fluorine ions on the surface of the phosphor to form insoluble fluorides;
3) MF ₆ ^2- complex ion is hydrolyzed and MO ₂ oxide is formed on the surface of the phosphor.
Actually, the above three processes are considered to proceed almost simultaneously.

Since the phosphor matrix containing the alkaline earth metal silicate is weak to water, the present inventors have confirmed that the amount of alkaline earth metal eluted increases with the immersion time when immersed in water. . Therefore, it is considered that when the phosphor matrix is dispersed and brought into contact with an aqueous solution containing MF ₆ ^2- complex ions, an elution reaction of metal ions occurs similarly. However, unlike the case of pure water, in the aqueous solution containing MF ₆ ^2- complex ions, free fluorine ions are present in the solution according to the following reaction formula (6). It can react with fluorine ions near the surface of the phosphor to form an insoluble fluoride. It is considered that the progress of the metal elution reaction is suppressed by forming such an insoluble fluoride on the surface of the phosphor. In addition, silicon and oxygen become rich where alkaline earth metals are eluted. The formation of the silicon-oxygen rich layer (intermediate layer) is also considered to function to suppress the continuous elution of alkaline earth metal.
Further, fluorine ions are consumed by the reaction between the alkaline earth metal and fluorine ions. As can be seen from the reaction formula (7), when fluorine ions are consumed, the hydrolysis reaction of MF ₆ ^2- complex ions is promoted, and the reaction proceeds to the right. As a result, MO ₂ oxide is formed. As described above, since the MO ₂ oxide has a very high stability to water, the moisture resistance of the phosphor is further improved by the formation of MO ₂ .

MF ₆ ²⁻ + nH ₂ O → [TiF _6-n (OH) _n ] ²⁻ + nH ⁺ + nF ⁻ (6)
MF ₆ ²⁻ + 2H ₂ O → MO ₂ + 4H ⁺ + 6F ⁻ (7)
BO ₃ ³⁻ + 6H + + 4F ⁻ → BF ⁴ + + 3H ₂ O (8)

The concentration of the MF ₆ ^2- complex ion during the reaction is preferably 0.0005 to 2.0M, more preferably 0.001 to 1.0M, and still more preferably 0.005 to 0.5M. . When the MF ₆ ^2- complex ion concentration is too low, deterioration due to hydrolysis of the phosphor cannot be suppressed during the treatment process. On the other hand, if the MF ₆ ^2- complex ion concentration is too high, the solution itself may become unstable or the reaction may be too fast, making it difficult to obtain a good film.

In order to accelerate the reaction rate of the hydrolysis reaction, an appropriate amount of hydrolysis accelerator may be added. The hydrolysis accelerator used in the present invention can be selected from compounds containing boron (B) or aluminum (Al). As shown in the above formula (8), boron or aluminum can form a stable complex with fluorine ions. The compound containing boron and the compound containing aluminum may be used alone or in combination of two or more.

Examples of the boron-containing compound include boron oxide, sodium tetraborate, boric acid (H ₃ BO ₃ ), and the like. Of these, boric acid is preferred.
Examples of the aluminum-containing compound include AlCl ₃ , AlBr ₃ , aluminum hydroxide (Al (OH) ₃ ), and the like.

The amount of the hydrolysis accelerator with respect to the MF ₆ ^2- complex ion is not particularly limited, but usually the amount of the hydrolysis accelerator with respect to 1 mol of MF ₆ ^2- complex ion is 0.1 mol or more, preferably It may be about 0.2 to 5 mol, more preferably about 0.5 to 4 mol.

The reaction time may be appropriately adjusted according to the reaction conditions such as the desired thickness of the intermediate layer and the surface layer, the concentration of the reaction solution, temperature, etc., and is usually about 5 minutes to 20 hours, preferably 10 minutes to 10 hours. Degree.
In general, if the amount of the prepared phosphor is constant, the film thickness increases as the reaction time increases. If the reaction time is too short, the formation of the oxide layer becomes incomplete. On the other hand, if the reaction time is too long, it is uneconomical.
What is necessary is just to adjust reaction temperature suitably according to the thickness of the target oxide layer, Usually, about 0-90 degreeC, Preferably it is about 5-70 degreeC, More preferably, what is necessary is just about 10-50 degreeC. .
The dispersion conditions during the reaction are not particularly limited as long as the phosphor can be dispersed. For example, magnetic stirrer stirring, mechanical stirring with a motor, gas barbbling, liquid circulation, ultrasonic dispersion, rotational dispersion such as a ball mill or a rotary mixer, or a combination of the above methods can be used.

After the reaction, the phosphor is recovered through filtration, washing and drying steps. Drying may be atmospheric drying or reduced pressure drying.
Moreover, in the said manufacturing method of a fluorescent substance, it is preferable to heat-process the said collect | recovered fluorescent substance at the temperature of 50-600 degreeC.

It is preferable that a water repellent layer is further formed on the outermost surface of the phosphor.
Forming the water repellent layer on the outermost surface has the following effects.
1) The water-repellent layer has a property of repelling water, and is expected to act to make moisture and water difficult to approach the surface of the phosphor. Thereby, the moisture resistance of the phosphor can be further improved. In order to improve the moisture resistance of the phosphor, it is important that moisture and water do not exist near the surface of the phosphor.
2) The dispersibility of the phosphor in the resin can be improved. A pure inorganic phosphor basically has a low affinity with a resin, but the affinity with a resin can be improved by forming a monolayer-level water-repellent layer on the surface. Further, since the water repellent layer has a monomolecular thickness, it can be ignored as compared with the thickness of the surface layer.
The water repellent layer is preferably made of a fluorine-containing compound.

(Method for forming water repellent layer)
Examples of the method for forming the water-repellent layer made of the fluorine-containing compound include a method of treating in a solution in which a fluorine-based silane coupling agent is dissolved.
Examples of the fluorine-containing coupling agent include trifluoropropyltrimethoxysilane (CF ₃ CH ₂ CH ₂ Si (OCH ₃ ) ₃ ), triethoxy-1H, 1H, 2H, 2H-tridecafluoro-n-octylsilane. _{(CF 3 (CF 2) 5} CH 2 CH 2 Si (OC 2 H 5) 3), trimethoxy -1H, 1H, 2H, 2H- tridecafluoro -n- octyl silane _{(CF 3 (CF 2) 5} CH 2 _{CH 2 Si (OCH 3) 3} ), 1H, 1H, 2H, 2H- perfluoro decyltrimethoxysilane _{(CF 3 (CF 2) 5} CH 2 CH 2 Si (OCH 3) 3) , and the like.

What is necessary is just to select suitably according to the kind of fluorine-type coupling agent as a solvent which dissolves the said fluorine-type coupling agent. For example, water, alcohols such as methanol, ethanol, and isopropanol, and a mixture of water and alcohol are suitable. In order to accelerate the hydrolysis reaction, an appropriate amount of acid (acetic acid, hydrochloric acid, nitric acid, sulfuric acid, etc.) may be added to the solvent.
As a density | concentration of the said fluorine-type coupling agent, the range of 0.1-5 weight% is preferable with respect to the quantity of fluorescent substance, and 0.5-2 weight% is more preferable.

When forming the water repellent layer, the treatment time is preferably 5 minutes to 5 hours, more preferably 10 minutes to 3 hours. After processing for the said predetermined time, after taking out fluorescent substance from a solution, filtering and wash | cleaning, it dries at the temperature of 100-150 degreeC. The drying time is preferably 1 to 60 minutes.
In addition to the wet method, the water-repellent layer can be formed by a dry method. As a dry method, for example, a method of spraying a fluorescent solution dispersed by dry stirring with a stock solution of the fluorine-containing silane coupling agent or a diluted solution diluted with an appropriate solvent can be applied.
As another form of the dry method, atmospheric pressure plasma treatment in a fluorine-containing reactive gas diluted with an inert gas such as argon can be used. The fluorine-containing reactive gas can be selected from fluorinated hydrocarbons such as CF ₄ , C ₂ F ₄ , C ₃ F ₆ , C ₄ F ₈ , and CHF ₃ .

The thickness of the water repellent layer is usually 5 nm or less, although it depends on the molecular chain length of the fluorine-based coupling agent.

(3-2) Sealing resin As the sealing resin, for example, a thermoplastic resin, a thermosetting resin, a photocurable resin, or the like can be used. Specifically, for example, methacrylic resin such as polymethylmethacrylate; styrene resin such as polystyrene and styrene-acrylonitrile copolymer; polycarbonate resin; polyester resin; phenoxy resin; butyral resin; polyvinyl alcohol; Cellulose-based resins such as cellulose acetate butyrate; epoxy resins; phenol resins; silicone resins.
In particular, when a high-power light-emitting device is required, such as lighting, it is preferable to use a silicon-containing compound for the purpose of heat resistance, light resistance, and the like.

The silicon-containing compound refers to a compound having a silicon atom in the molecule, organic materials such as polyorganosiloxane (silicone-based material), inorganic materials such as silicon oxide, silicon nitride, and silicon oxynitride, and borosilicates and phosphosilicates. Examples thereof include glass materials such as acid salts and alkali silicates. Among these, silicone materials are preferable from the viewpoint of ease of handling.

The silicone material usually refers to an organic polymer having a siloxane bond as a main chain, and examples thereof include a compound represented by the following formula (9) and / or a mixture thereof.
(R ¹ R ² R ³ SiO _1/2 ) _M (R ⁴ R ⁵ SiO _2/2 ) _D (R ⁶ SiO _3/2 ) _T (SiO _4/2 ) _Q (9)
Here, R ¹ to R ⁶ may be the same or different and are selected from the group consisting of an organic functional group, a hydroxyl group, and a hydrogen atom. M, D, T, and Q are 0 to less than 1 and satisfy M + D + T + Q = 1.
When the silicone material is used for sealing a semiconductor light emitting device, it can be used after being sealed with a liquid silicone material and then cured by heat or light.
Examples of the type of the silicone material generally include an addition polymerization curing type, a condensation polymerization curing type, an ultraviolet curing type, and a peroxide crosslinking type. Among these, addition polymerization curing type (addition type silicone resin), condensation curing type (condensation type silicone resin), and ultraviolet curing type are preferable.

Although the manufacturing method of the LED light-emitting device of this invention is not specifically limited, For example, it can manufacture with the following method.
First, after mounting an LED chip on a substrate having leads, a resin frame having a cup-shaped recess whose opening is wider than the bottom is formed. Subsequently, it can produce by filling the recessed part with the fluorescent substance resin composition containing the fluorescent substance produced by the following method and sealing resin.

The method for producing the phosphor resin composition is not particularly limited as long as the phosphor is uniformly dispersed in the sealing resin.
Specifically, for example, a liquid sealing resin, a phosphor, a filler such as silica fine particles, a crosslinking agent, a curing catalyst, and other additives are blended, and mixed with a mixer, a high-speed disper, a homogenizer, a three-roll, a kneader, etc. can do. In this case, a liquid resin composition can be produced in the form of one liquid by mixing all the components. In addition, two liquids of (i) a liquid sealing resin and a phosphor-based resin composition, and (ii) a crosslinking agent and a curing catalyst as main components are prepared and immediately before use. The final liquid resin composition may be produced by mixing the resin composition and the crosslinking agent solution.

The blending amount of the phosphor in the phosphor resin composition is preferably 0.1 parts by weight or more, more preferably 0.5 parts by weight or more with respect to 100 parts by weight of the sealing resin. More preferably, it is at least part by weight. Moreover, it is preferable that it is 100 weight part or less with respect to sealing resin, It is more preferable that it is 80 weight part or less, It is still more preferable that it is 60 weight part or less. If the amount of the phosphor is too small, a desired light emission amount cannot be obtained, and if it is too large, the cost is increased and this is disadvantageous in terms of economy.

The application of the LED light-emitting device of the present invention is not particularly limited, and can be used in various fields where a normal LED light-emitting device is used. Moreover, you may use individually or in combination. Specifically, for example, it can be used as a light source for illumination lamps, backlights for liquid crystal panels, various illumination devices such as ultra-thin illumination, and image display devices. In addition, when using the LED light-emitting device of this invention as a light source of an image display apparatus, you may use together with a color filter.

According to the present invention, it is possible to prevent surface degradation due to water vapor or water in the air, and it is excellent in moisture resistance that does not cause a decrease in light intensity or change in color tone even when used in a long time or high temperature and high humidity environment. As a result, it is possible to obtain an LED light-emitting device in which the luminous intensity does not easily decrease even in a high-temperature and high-humidity environment.

It is a cross-sectional schematic diagram of the LED light-emitting device of this invention. It is a cross-sectional schematic diagram of the fluorescent substance used for the LED light-emitting device of this invention. 2 is an FE-TEM cross-sectional photograph of the surface-treated phosphor obtained in Example 1. FIG.

Examples of the present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples.

[Example 1]
A green silicate phosphor (mainly having a median particle size (D ₅₀ ) of about 16 μm was added to 250 ml of a mixed aqueous solution containing 0.1 mol / L ammonium titanium fluoride ((NH ₄ ) ₂ TiF ₆ ) and 0.1 mol / L boric acid. Ingredients: (Ba, Sr) ₂ SiO ₄ : Eu ²⁺ ) 12.5 g was added.
The mixture was added with the phosphor and stirred at 35 ° C. for 2 hours while being dispersed. After the reaction, the phosphor recovered through filtration and washing steps was vacuum-dried at 120 ° C. for 1 hour.
In addition, the FE-TEM cross-sectional photograph of the obtained surface treatment fluorescent substance is shown in FIG.

8 parts by weight of the obtained phosphor was mixed and dispersed with respect to 100 parts by weight of a silicone resin (manufactured by Dow Corning, OE6630), and defoamed to prepare a phosphor resin composition. Next, an LED chip (emission peak wavelength 460 nm) as shown in FIG. 1 is mounted on the prepared phosphor resin composition, and a resin frame having a cup-shaped recess whose opening is wider than the bottom is formed. The resin composition was cured by injecting and filling on the substrate, and further heating at 150 ° C. for 2 hours to obtain an LED light-emitting device.

[Comparative Example 1]
As a phosphor, a green silicate phosphor (main component: (Ba, Sr) ₂ SiO ₄ : Eu ²⁺ ) having no surface layer and no intermediate layer and having an untreated surface median particle diameter (D ₅₀ ) of about 16 μm An LED light-emitting device was produced in the same manner as in Example 1 except that it was used.

(Evaluation methods)
<Electrical characteristics evaluation>
The LED light-emitting devices obtained in the examples and comparative examples were energized for 1000 hours at a current of 20 mA in an atmosphere having a pressure of 1 atmospheric pressure, a temperature of 85 ° C. and a relative humidity of 85%, and the luminous intensity before and after the energization was measured. Note that an OL770 measuring system manufactured by Optronic Laboratories was used as the measuring apparatus.
And the retention rate of the luminous intensity after electricity supply with respect to the luminous intensity before electricity supply was computed. Moreover, relative humidity resistance was evaluated from the obtained luminous intensity retention. The results are shown in Table 1.

ADVANTAGE OF THE INVENTION According to this invention, since it is excellent in the moisture resistance of fluorescent substance, the LED light-emitting device which a light intensity cannot fall easily also in a high temperature and humidity environment can be provided.

Claims (5)

An LED light emitting device comprising an LED chip, a resin frame surrounding the LED chip, and a phosphor layer filled in a recess formed by the resin frame,
The phosphor layer contains a phosphor and a sealing resin,
The phosphor has a phosphor matrix, an intermediate layer, and a surface layer toward the outermost surface, the molar ratio of alkaline earth metal to silicon is 1.5 or more, and
The LED light emitting device has a luminous intensity retention of 90% or more after being energized for 1000 hours under conditions of a temperature of 60 to 90 ° C., a relative humidity of 60 to 90%, and a current of 20 to 120 mA. The phosphor has a phosphor matrix containing an alkaline earth metal, an intermediate layer containing an alkaline earth metal, an alkaline earth metal, an element of Groups 4 to 6 in the periodic table, toward the outermost surface, A phosphor having a surface layer containing at least one selected from yttrium and silicon,
2. The LED light emitting device according to claim 1, wherein the alkaline earth metal content in the phosphor matrix, the intermediate layer, and the surface layer satisfies the following expressions (1) and (2): 3.
In the formula, C ₁ represents the content of alkaline earth metal in the phosphor matrix, C ₂ represents the content of alkaline earth metal in the intermediate layer, and C ₃ represents the content of alkaline earth metal in the surface layer. 3. The LED light-emitting device according to claim 1, wherein the phosphor matrix has a structure represented by the following formula (3).
In formula (3), M is at least one selected from the group consisting of Mg, Ca, Ba, and Zn, and x and y are 0 ≦ x ≦ 0.5, 2.6 ≦ y ≦ 3.3, respectively. Is within the range. The LED light-emitting device according to claim 1 or 2, wherein the phosphor matrix has a structure represented by the following formula (4).
In Formula (4), L1 is at least one selected from the group consisting of Mg, Ca, Ba and Zn, and L2 is at least selected from the group consisting of B, Al, Ga, C, Ge, N and P. L3 is at least one selected from the group consisting of F, Cl, Br, N and S, and x is 1.5 to 2.5. The LED light-emitting device according to claim 1, wherein the phosphor matrix has a structure represented by the following formula (5).
In formula (5), M1 and M2 are at least one selected from the group consisting of Mg, Ca, Ba, and Zn, and a, x, y, z, and u are each 0.6 ≦ a ≦ 0.85. 0.3 ≦ x ≦ 0.6, 0.85 ≦ y ≦ 1, 1.5 ≦ z ≦ 2.5, 2.6 ≦ u ≦ 3.3.