KR20150031393A

KR20150031393A - Light emitting device having scattering particle

Info

Publication number: KR20150031393A
Application number: KR20130110751A
Authority: KR
Inventors: 강영래; 김동설
Original assignee: 일진엘이디(주)
Priority date: 2013-09-14
Filing date: 2013-09-14
Publication date: 2015-03-24

Abstract

The present invention relates to a light emitting device having a scattering particle. The present invention disperses uniformly scattering particles without condensation or deposition and implements color uniformity without degradation of brightness. The device seals the light emitting diode to be installed on a lead frame and includes an encapsulant in which the scattering particle and nano powder are dispersed.

Description

[0001] The present invention relates to a light emitting device having scattering particles,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device, and more particularly, to a light emitting device including scattering particles having similar physical properties to a plug body to improve color uniformity of the light emitting device.

Light emitting diodes (LEDs) convert electrical energy into light, and light is generated in at least one active layer between layers doped with impurities, which are generally of opposite polarity. That is, when a bias is applied to both sides of the active layer, holes and electrons are injected into the active layer and recombined to generate light. Such light is emitted to the outside from the active layer and the entire surface of the light emitting diode. The light emitting diode is sealed in a package to provide various functions such as protection from external environmental or mechanical damage, color selection, focusing of light, and the like.

On the other hand, the light emitting device generates a desired color using a phosphor containing phosphorus contained in the plug. That is, the light emitted from the light emitting device reacts with the phosphor, and the scattering particles are uniformly dispersed in the plug to uniformly react the light with the phosphor. The use of the scattering particles not only increases the probability of reacting with the phosphor by varying the path of light emitted from the light emitting device, but also provides a path through which the changed light can escape, thereby enabling uniform emission. In other words, color uniformity can be secured not only at the center of the light emitting element but also at the outer periphery thereof by scattering particles.

However, in a light emitting device including scattering particles in the past, scattering particles often have a specific gravity higher than that of the plugs and sink or coexist, and often fail to fully exhibit their function as scattering particles. Particularly, the scattering particles may be layered or locally aggregated to be deposited around the light emitting device. As a result, the light emitted from the light emitting device passes through the scattering particles and the brightness is lowered. As a result, . In addition, even when scattering particles are added, color uniformity is not achieved over the entire light emitting device due to the precipitation and aggregation, and color irregularity occurs, for example, in the center and the periphery of the light emitting device.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a light emitting device including scattering particles capable of realizing color uniformity without causing aggregation or precipitation and uniformly dispersing scattering particles so that luminance does not decrease.

A light emitting device including scattering particles to solve the problems of the present invention includes a light emitting diode mounted on a lead frame and a plug sealing the light emitting diode and scattering particles and nano powder dispersed therein. At this time, the nano powder preferably has a size smaller than ½ of the wavelength of light generated in the chip.

In the device of the present invention, the difference in refractive index between the scattering particles and the plugs is preferably 0.10 to 0.15, and may be selected from among silicon powder, silicone resin and epoxy resin. The average diameter of the scattering particles is preferably 2 탆 to 15 탆, and the scattering particles may be added in an amount of 0.5 to 2% by weight based on the total weight of the plugs. The nano powder may be at least one selected from the group consisting of silica, silica hollow spheres, glass, alumina, PMMA beads, and nano-sized polystyrene beads. . In the present invention, the scattering particles and the nano powder may be distributed in an upper region of the plug and may be distributed in a lower region of the plug.

According to the light emitting device including the scattering particles of the present invention, scattering particle microspheres having similar physical properties to the plugging material are dispersed in the plug together with the nano powder to prevent aggregation or precipitation of scattering particles, So that the luminance is not deteriorated and the color uniformity can be realized. In addition, the scattering layer containing the scattering particles can be restricted to a certain region of the plug, so that the scattering effect can be sufficiently obtained while reducing the amount of the scattering particles and the nano powder.

1 is a cross-sectional view conceptually illustrating a first light emitting device including scattering particles according to an embodiment of the present invention.
2 is a cross-sectional view conceptually illustrating a second light emitting device including scattering particles according to another embodiment of the present invention.
3 is a cross-sectional view conceptually illustrating a third light emitting device including scattering particles according to another embodiment of the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiments described below can be modified into various other forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to enable those skilled in the art to more fully understand the present invention.

In the embodiment of the present invention, scattering particle microspheres having similar physical properties to the plug body are dispersed in the plug together with the nano powder, so that the scattering particles do not aggregate or precipitate and are uniformly dispersed, And a light emitting device including scattering particles capable of realizing color uniformity. For this purpose, a detailed description will be made of a process in which scattering particle microspheres and nano powder are dispersed in the bag, and the color uniformity of the light emitting device is improved. Meanwhile, the light emitting device to which the present invention is applied can be variously formed regardless of the presence or absence of the reflection cup within the scope of the present invention. Here, for example, a light-emitting element having a reflection cup.

1 is a cross-sectional view conceptually illustrating a first light emitting device 100 including scattering particles according to an embodiment of the present invention. Here, for convenience of explanation, scattering particles and nanoparticles dispersed in a plug body are conceptually expressed, and therefore, they may be different from actual ones.

1, a first light emitting device 100 includes a substrate 10, a lead frame 20 disposed at predetermined intervals on the substrate 10, a light emitting diode 22 mounted on the lead frame 20, And a wire 24 connecting the light emitting diode 22 to the lead frame 20. At this time, the light emitting diode 22 is disposed in a cavity of the cup structure defined by the side wall 30 serving as a reflecting cup. The first light emitting device 100 has a structure in which a light emitting diode 22 is mounted in the cavity, and then the cavity is filled with a plug 40 such as silicone resin. At this time, the scattering particles 50, which are microspheres, are dispersed in the plugs 40 together with the nano powder 52.

The scattering particles 50 according to the present invention are materials of the same system although they differ from the bag 40 in refractive index. Specifically, if the plug body 40 is a silicone-based material, the scattering particles 50 are preferably silicon-based micro spheres. If the plugs 40 are epoxy-based materials, the scattering particles 50 are preferably epoxy-based micro spheres. That is, by making the physical properties of the plugs 40 and the scattering particles 50 similar to each other except the refractive index, it is possible to prevent deterioration of the light emitting device due to a change in the external environment, for example, shrinkage and expansion due to heat. On the other hand, the difference between the refractive indexes of the plugs 40 and the scattering particles 50 is preferably 0.10 to 0.15. When the difference is less than 0.10, the scattering effect is small, and when it is larger than 0.15, it is difficult to obtain uniform scattering. The scattering particles 50 of the embodiment of the present invention used silicon-based microspheres having a refractive index of about 1.42 so as to correspond to the silicon-based plugs 40 having a refractive index of about 1.53.

In addition, the scattering particles 50 of the present invention are preferably spherical. Here, the spherical shape is a particle having a curvature enough to obtain a scattering effect within the scope of the present invention, and does not necessarily mean a complete spherical shape. If the scattering particles 50 are spherical, a stable scattering effect can be obtained. The spherical scattering particles 50 can lower the viscosity and increase the amount of the scattering particles 50 to be added and have little effect on the shrinkage and warpage of the plugs 40, Cause. That is, when light having a hue is incident on the scattering particles 50, scattering occurs with a uniform probability, and a haze phenomenon that is partially blurred can be prevented.

The size of the scattering particles 50 may vary depending on the size and shape of the first light emitting device 100 and the plugs 40, but may be an average diameter of 2 탆 to 15 탆. If the diameter is less than 2 탆, it is difficult to control the amount of the scattering particles 50 and the dispersion thereof. If the diameter is larger than 15 탆, the scattering effect is excessively increased. The silicon-based scattering particles 50 may be a silicon powder or a silicone resin that maintains the refractive index difference with the silicon-based plug 40. In the case of the silicone resin, the silicon in the form of a siloxane bond (Si-O bond) may be a back-bone, and a functional group such as a methyl group, a phenyl group, or a hydroxyl group may be bonded to the silicon. The epoxy-based scattering particles 50 may be a resin that maintains the refractive index difference with the epoxy-based plug body 40 and is a thermosetting resin having an epoxy group in the molecule and a functional group such as an unsaturated monomer bonded to the epoxy group.

The nanopowder 52 is well dispersed in the encapsulant 40 as well as transmitting light. The nanopowder may be silica, silica spheres, glass, alumina, PMMA beads, , And nano-sized polystyrene beads. Of these, silica is preferable. The nano powder 52 has a size smaller than ½ of the wavelength of light generated by the light emitting diode 22, and the light is transmitted. That is, the nano powder 52 does not affect scattering of light, but prevents the scattering particles 50 of the present invention from precipitating in the direction of the light emitting diode 22 and enhances dispersibility of the scattering particles 52 . Further, the nano powder 52 can also have a side effect of preventing the phosphor containing phosphorus from precipitating in the direction of the light emitting diode 22. The amount of the scattering particles 50 according to the embodiment of the present invention can be appropriately selected in consideration of the amount of the nano powder 52, the physical properties of the plugs 40, scattering of light, etc. However, 0.5 to 2% by weight.

The first light emitting device 100 according to the embodiment of the present invention is such that the scattering particles 50 having similar physical properties to the plugs are mixed with the nano powder 52 and uniformly dispersed in the plug without causing precipitation or aggregation . Accordingly, the uniformly dispersed scattering particles 50 do not cause a decrease in luminance of the first light emitting device 100. [ In addition, due to the scattering effect of the uniformly dispersed scattering particles 50, the color uniformity of the first light emitting device 100 can be realized. That is, the uniformly scattered light uniformly hues the entire region of the first light emitting device 100 over the central portion and the outer periphery thereof.

2 is a cross-sectional view conceptually illustrating a second light emitting device 200 including scattering particles according to another embodiment of the present invention. Here, the second light emitting device 200 is the same as the first light emitting device 100 except that the scattering particles 50 and the nano powder 52 are located in the upper region a of the plug body 40 . Accordingly, the same reference numerals as those of the first light emitting device 100 have the same functions and functions, and a detailed description thereof will be omitted.

2, in the second light emitting device 200, the scattering layer including the scattering particles 50 and the nano powder 52 is located in the upper region a of the plugs 40. At this time, the upper region (a) is a region including the scattering particles 50 and the nano powder 52, and one side thereof is exposed to the outside of the second light emitting device 200. The scattering layer is formed in the upper region a of the plug body 40 so that the scattering effect to be obtained in the present invention can be sufficiently obtained while reducing the use amount of the scattering particles 50 and the nano powder 52 . The thickness of the upper region a may be determined by the shape of the light emitting device and the like and the amount of the scattering particles 50 and the nanopowder 52 may be appropriately adjusted within the range indicated by the first light emitting device 100 .

Even when the scattering layer is limited to the upper region (a) as in the second light emitting device 200 of the present invention, the scattering effect to be pursued in the present invention can be sufficiently secured. By limiting the scattering layer in this manner, it is easy to obtain a uniform dispersion of the scattering particles 50 as compared with the first light emitting device 100. Actually, since the first light emitting device 100 forms a scattering layer on the entire encapsulant, the dispersion uniformity of the scattering particles 50 may be lower than that of the second light emitting device 200. However, since the second light emitting device 200 requires a separate process for forming the scattering layer, the manufacturing cost may increase. Accordingly, any one of the first and second light emitting devices 100 and 200 can be selected according to a desired scattering effect and a manufacturing cost.

3 is a cross-sectional view conceptually illustrating a third light emitting device 300 including scattering particles according to another embodiment of the present invention. The third light emitting device 300 is the same as the first light emitting device 100 except that the scattering particles 50 and the nano powder 52 are located in the lower region b of the plug body 40 . Accordingly, the same reference numerals as those of the first light emitting device 100 have the same functions and functions, and a detailed description thereof will be omitted.

3, in the third light emitting device 300, a scattering layer including scattering particles 50 and nanoparticles 52 is located in the lower region b of the plug 40. As shown in FIG. The lower region b is a region including the scattering particles 50 and the nano powder 52 and is located below the plugs 40 while covering the light emitting diodes 22. The scattering layer is formed in the lower region b of the plug body 40 so that the scattering effect to be obtained in the present invention can be sufficiently obtained while reducing the amount of the scattering particles 50 and the nano powder 52 used. The thickness of the lower region b may be determined depending on the shape of the light emitting device and the amount of the scattering particles 50 and the nano powder 52 may be appropriately adjusted within the range indicated by the first light emitting device 100 .

Even if the scattering layer is limited to the lower region (b) as in the third light emitting device 300 of the present invention, there is no problem in obtaining a scattering effect to be pursued in the present invention. By limiting the scattering layer in this manner, it is easy to obtain a uniform dispersion of the scattering particles 50 as compared with the first light emitting device 100. In practice, since the first light emitting device 100 forms a scattering layer on the entire encapsulant, the dispersion uniformity of the scattering particles 50 may be lower than that of the third light emitting device 300. However, since the third light emitting device 300 requires a separate process for forming the scattering layer, the manufacturing cost may increase. Accordingly, any one of the first and third light emitting devices 100 and 300 can be selected according to a desired scattering effect and manufacturing cost. Further, the third light emitting device 300 can be relatively free from the precipitation of the scattering particles 50 because the scattering layer is located in the lower region (b).

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but many variations and modifications may be made without departing from the spirit and scope of the invention. It is possible.

10; A substrate 20; Lead frame
22; A light emitting diode 24; wire
30; Side walls 40; The bag body
50; Scattering particles 52; Nano powder
100, 200, 300; The first to third light emitting elements

Claims

A light emitting diode mounted on a lead frame; And
A light emitting device comprising scattering particles including scattering particles and a plug including a nano powder having a size smaller than 1/2 of the light wavelength generated in the chip.

The light emitting device according to claim 1, wherein the scattering particles and the plugs have different refractive indices.

The light emitting device according to claim 1, wherein a difference in refractive index between the scattering particles and the plug is 0.10 to 0.15.

The light emitting device according to claim 1, wherein the scattering particles are selected from the group consisting of silicon powder, silicone resin, and epoxy resin.

The light emitting device according to claim 1, wherein the average diameter of the scattering particles is 2 占 퐉 to 15 占 퐉.

The light emitting device according to claim 1, wherein the scattering particles are added in an amount of 0.5 to 2% by weight based on the total weight of the plug.

The method of claim 1, wherein the nano powder is at least one selected from the group consisting of Silica, Silica Hollow Spheres, Glass, Alumina, PMMA bead, Nano-sized polystyrene bead Wherein the scattering particles are scattered by the scattering particles.

The light emitting device according to claim 1, wherein the scattering particles and the nano powder are distributed in an upper region of the plug.

The light emitting device according to claim 1, wherein the scattering particles and the nano powder are distributed in a lower region of the plug.