KR20080056424A - Light emitting device package and method for manufacturing it - Google Patents

Abstract

An LED(light emitting diode) package is provided to improve the light efficiency by adjusting the angle of light projected to the outside of an LED package. A filling material is formed on a light emitting device. A lens(330) is formed on the filling material, having a non-uniform distribution of refractivity. The refractivity of the lens becomes smaller as it goes from the center of the lens to the outer part of the lens. A reflection layer(315) can be formed on the bottom and/or the wall of the inside of a body to which the light emitting device is fixed.

Description

Light emitting device package and method for manufacturing the same

1 is a view showing a photorefractive function of a light emitting device package having a conventional spherical lens,

2 is a view showing a photorefractive function of a light emitting device package having an aspherical lens,

3 is a view showing an embodiment of a lens provided in a light emitting device package according to the present invention,

4 is a view showing an embodiment of a reflective layer formed on a body having a light emitting device;

5 is a view showing an embodiment of a light emitting device package according to the present invention,

6 is a view showing another embodiment of a light emitting device package according to the present invention;

7a to 7d are views showing still another embodiment of a light emitting device package according to the present invention,

8a to 8f are views showing a first embodiment of a method of manufacturing a light emitting device package according to the present invention;

9A to 9F illustrate a second embodiment of a method of manufacturing a light emitting device package according to the present invention.

<Explanation of symbols for the main parts of the drawings>

100 body 110 light emitting element

120: filler 130, 130 ': lens

150, 150 ': optical path 315: reflective layer

330: Lens 330 ': Refraction

340: optical layer 350: auxiliary substrate

The present invention relates to a light emitting device package, and more particularly, to provide a light emitting device package having improved light efficiency and a method of manufacturing the same.

A light emitting diode, which is one of light emitting devices, is a device using a semiconductor characteristic that emits light, and is different from a conventional light emitting device that generates light by a discharge or heating method. That is, compared with the conventional light emitting element such as a light bulb or a fluorescent lamp, the light emitting diode has characteristics such as high durability, long life, high brightness and low power consumption.

Specifically, the light emitting diode is composed of a junction between a p-type and an n-type semiconductor, and when a voltage is applied, the optoelectronic device emits energy corresponding to a bandgap of the semiconductor in the form of light by combining electrons and holes. )to be. In addition, the light emitting diode has excellent optical characteristics such as color rendering ability, color rendering ability, and PWM driving, and is widely used in various fields such as display and lighting.

However, the light emitting diode package including the conventional light emitting diode described above has the following problems.

Direct use of light emitting diodes in applications makes it difficult to achieve the desired performance because the spatial distribution of the luminous flux emitted from the light emitting diodes is not suitable. Therefore, a lens that is primarily combined with a light emitting diode is required to control luminous flux. When manufacturing a lens with performance in mind, the lens has an aspherical shape or a complicated pattern, which increases manufacturing cost and complicates the process, thereby lowering the yield. There is a problem.

That is, as shown in FIG. 1, a light emitting device 110 such as a light emitting diode is provided inside the body 100, and an encapsulate material 120 is formed on the light emitting device. Here, the filler is made of silicon or epoxy to protect the light emitting diode chip. A spherical lens 130 is formed on the filler to change the projection angle of light emitted from the light emitting device.

Here, since the refractive index of the material constituting the filler and the lens does not vary significantly, the angle at which light is refracted at the interface between the filler and the lens is not large. However, the refractive index between the lens and the air is different, so the angle at which light is refracted at the lens surface is large. Therefore, the light projected to the outside of the light emitting device package is refracted in the external direction 150 'than the refraction direction 150 required for the performance, there is a problem that the light efficiency such as condensation is lowered. That is, the light emitting device package provided with the spherical lens can reduce the manufacturing cost and simplify the process, but there is a problem that the light efficiency is lowered as described above.

2 is a view illustrating a light refractive function of a light emitting device package having an aspherical lens 130 ′. In FIG. 2, since the shape of the lens is formed as an aspherical surface, the angle of light projected from the lens to the outside may be reduced, and thus the optical efficiency may be improved by securing a refractive direction required for performance according to the design of the aspherical surface.

However, the light emitting device package provided with the aspherical lens can satisfy the above-described performance and reduce the thickness, but there are disadvantages in that the manufacturing cost increases and is not suitable for mass production.

The present invention is to solve the above problems, an object of the present invention is to provide a light emitting device package with improved light efficiency by adjusting the angle of the light projected to the outside.

Another object of the present invention is to provide a method for mass production of a light emitting device package having improved light efficiency by controlling the angle of light projected to the outside at low cost.

In order to achieve the above object, the present invention is a filler formed on a light emitting device; And a lens formed on the filler and having a non-uniform refractive index distribution.

According to another embodiment of the invention, preparing a light emitting device sealed with a filler; And exposing a lens material substrate on the light emitting device to form a lens having a non-uniform refractive index distribution.

According to another embodiment of the invention, forming a wafer level lens substrate on a wafer level package having a plurality of light emitting elements; Exposing the wafer level lens substrate to form a plurality of lenses having a non-uniform refractive index distribution; And separating the wafer level package and the plurality of lenses for each device to form a plurality of light emitting device packages.

Hereinafter, with reference to the accompanying drawings, preferred embodiments of the present invention that can specifically realize the above object will be described.

The same components as in the prior art are given the same names and the same reference numerals for convenience of description, and detailed description thereof will be omitted.

The light emitting device package according to the present invention is characterized in that the cross section is planar, unlike a conventional lens having a convex cross section. And, in order to adjust the refractive direction of the light passing through the lens, it is characterized in that the refractive index is different for each point of the lens. In addition, the reflective surface is formed inside the body of the package provided with a light emitting device for improving the light efficiency.

3 is a view showing an embodiment of a lens provided in a light emitting device package according to the present invention, Figure 4 is a view showing a reflective surface formed on the body provided with a light emitting device. An embodiment of a lens and a reflective surface provided in the light emitting device package according to the present invention will be described with reference to FIGS. 3 and 4 as follows.

In FIG. 3, the lens 330 has a disc shape. Here, the disc means that the plane of the lens is circular and the cross section is rectangular. In addition, it does not mean that it is exactly disk shape geometrically, but it means that it is distinguished from the conventional lens which a convex center. In addition, although the conventional lens has a structure having a constant refractive index as a whole, in the present embodiment, the refractive index distribution is not uniform. Specifically, the refractive index of the lens is characterized in that it becomes smaller toward the outer from the center, it is given by the following equation.

Here, p denotes a distance from the center of the lens, and n (ρ) denotes a refractive index at a point where the distance from the center of the lens is p. Therefore, the refractive index at the center is about 2.2. The lens has a thickness of 0.8 to 1.2 millimeters and a focal length of 2.0 to 3.0 millimeters. Here, the thickness and the focal length of the lens is a value suitable for the light emitting device package currently used, and may be modified according to the use and the size of the package.

In addition, the lens is characterized in that it comprises a material selected from the group consisting of LiNbO ₃ , KTaO ₃ , KNbO ₃ , BaTiO ₃ and SrNb ₂ O ₃ in addition to the usual material. The above-described light modulation materials are included in the lens, and the electron arrays are different according to the distance from the center, thereby representing a difference in refractive index. Here, a specific manufacturing method of the lens will be described later.

In addition, in FIG. 4, the light emitting device 310 is provided on a portion of the bottom surface of the body 300 constituting the package. The light emitting device may be a light emitting diode but may be another light emitting device. That is, the present invention is to improve the light efficiency by adjusting the refractive index of the light emitted from the light emitting device package, it is sufficient if the light emitting device is provided inside the package. As shown in the drawing, a reflective layer 315 is preferably formed on at least one of the bottom surface and the wall surface of the body. The reflective layer may be made of aluminum, silver, or the like, and may be formed by a coating method or the like.

5 is a view showing an embodiment of a light emitting device package according to the present invention. In FIG. 5, the light emitting device package includes a light emitting device 310 on a portion of the bottom surface of the body 300, and a reflective layer 315 is formed on the bottom surface and / or the wall surface of the body 300. The light emitting device is sealed with the filler 320, and the lens 330 described above is formed on the filler. As described above, the lens has the largest refractive index at the center portion, and the refractive index decreases toward the outer side.

In the present embodiment, the light emitted from the light emitting element is directed to the lens through the filler. At this time, some of the light reflected at the interface between the lens and the filler may be reflected by the above-described reflective layer and proceed back to the lens, thereby improving the light efficiency. Then, the light incident on the lens proceeds to the outside by refracting the direction of travel according to Snell's law. Here, since the center of the lens has a higher refractive index than the edge, the angle at which light is refracted is also large. That is, the light may proceed to the outside at the center of the lens, but the edge of the lens is relatively more straight. Therefore, the linearity of light emitted from the light emitting device package to the outside may be improved as a whole.

6 is a view showing another embodiment of a light emitting device package according to the present invention. This embodiment is the same as the embodiment shown in FIG. 5, but the optical layer 340 is formed. Here, the optical layer may be made of air or a low refractive index film, and the refractive index is smaller than that of the filler to selectively transmit the light emitted from the light emitting device. The optical layer may be formed on one surface of the lens to be interviewed with the filler, and may be formed in a dimple shape as shown. That is, one surface of the lens is dug into the groove, and air or a low refractive index film is injected into the groove to form an optical layer.

In FIG. 6, light emitted from the light emitting device 310 provided in the body 300 passes through the filler 320 and proceeds to the optical layer 340. Since the light is incident on the optical layer at an angle less than the critical angle θ _c , light passes through the lens 330 and travels outside the LED package.

If the light is incident on the optical layer at an angle exceeding the critical angle, all of the light is reflected at the interface between the filler and the optical layer, and then proceeds back to the filler. Here, total reflection occurs when the incident angle exceeds a certain angle (critical angle) when light is incident from an optically dense medium (a material having a large refractive index) to a small medium (a material having a small refractive index). It means the phenomenon that all the light is reflected at the interface and the refracted ray does not exist. The minimum value of the incident angle at which total reflection can occur is called a critical angle. Here, the critical angle is determined according to the physical properties of the filler and the optical layer, specifically, the refractive index. If the refractive index of the filler is n ₁ and the refractive index of the optical layer is n ₂ In this case, the critical angle is determined by the following equation.

Here, the refractive index of the lens is preferably larger than the refractive index of the optical layer. In addition, as described above, total reflection of light may occur at the interface between the filler and the optical layer, and thus the light efficiency may be deteriorated. However, since the reflective layer is formed on the bottom surface and / or the wall inside the body, the light totally reflected by the optical layer Can be reflected back into the filler. Here, only light incident at an angle less than the critical angle θ _c may be incident to the optical layer, and light incident above the critical angle is reflected and proceeds back to the filler. The light incident on the optical layer is refracted and proceeds. Since the incident angle is less than the critical angle, the refracted angle is also less than or equal to a predetermined angle. That is, since the angle of incidence into the optical layer is less than the critical angle, the angle of refraction is also limited within a predetermined angle according to Snell's law. Then, the light propagating from the optical layer to the lens is refracted at the boundary again to proceed.

That is, the light incident on the optical layer according to the above-mentioned total reflection phenomenon exists only when the angle is less than a predetermined angle, and therefore the light traveling through the lens is also different from the predetermined angle (the predetermined angle at which the light travels in the optical layer, Snell's law Can be calculated). Therefore, it is possible to secure the straightness of the light emitted from the light emitting element.

In addition, in FIG. 6, the lens 330 has a non-uniform refractive index distribution as described above. Therefore, the light is more straight at the edge than in the center of the lens, it is possible to further ensure the straightness of the light.

Therefore, the light emitting device package according to the present exemplary embodiment has excellent condensing performance, and sufficient refractive effect can be obtained even when using a flat lens instead of a convex shape. Therefore, it is possible to manufacture a wafer level lens substrate, and to reduce manufacturing cost and improve productivity.

7A to 7D are diagrams illustrating still other embodiments of a light emitting device package according to the present invention.

The embodiments are basically the same as the embodiment shown in FIG. 5 or 6, but part of the lens 330 is patterned 330 ′. Here, the present embodiment is characterized in that the patterned portion is formed in a portion of the lens to adjust the refractive angle of the light, thereby improving the light efficiency by adjusting the light propagation path.

In FIG. 7A, the surface of the lens in contact with the optical layer is patterned. In FIG. 7B, the surface opposite to the surface in contact with the optical layer is patterned. In FIG. 7C, both the first and second surfaces of the lens are patterned. Here, the first surface and the second surface mean a portion forming a circle among the surfaces of the lens. However, in the present embodiment, the circular surface is patterned and bumpy. In FIG. 7D, the optical layer is not provided, and the lens surface on the surface opposite to the surface in contact with the filler is patterned. In addition, although not shown in the drawing, even if the optical layer is not provided, both the lens surface of the surface in contact with the filler or both surfaces of the lens may be patterned.

In the embodiments shown in FIGS. 7A-7D, the light emitted from the light emitting element and passing through the filler and / or lens passes through the patterned portion, and the traveling path is changed. Accordingly, the light propagation path may be adjusted by changing the shape of the patterned part, and the patterned part may generally have the shape of a cylinder, a pyramid or a tetrahedron.

In addition, a scattering body may be provided in the lens to change the light traveling path. That is, although not shown in the drawing, if a micro scatterer is included in the lens, the light propagation path may be changed by scattering of light. In addition, the scatterer described above may be included in the filler or the optical layer in addition to the lens.

In the above-described embodiments, a material for changing the light propagation path is provided on the filler or the lens of the light emitting device package, thereby improving the light efficiency by adjusting the light propagation path emitted from the light emitting device.

8A to 8F illustrate a first embodiment of a method of manufacturing a light emitting device package according to the present invention.

First, the lens material substrate 330a is prepared as shown in FIG. 8A. Here, the lens material substrate may be made of a material selected from the group consisting of LiNbO ₃ , KTaO ₃ , KNbO ₃ , BaTiO _3, and SrNb ₂ O ₃ , and a lens having a non-uniform refractive index is formed through an exposure process to be described later. .

Subsequently, as shown in FIG. 8B, the body 300 of the light emitting device package having the light emitting device 310 therein is prepared. The light emitting device is filled with the filler 320, and the reflective layer 315 may be formed on the body as described above. In addition, the lens material substrate may be formed of a wafer level lens substrate capable of forming a plurality of lenses, and a plurality of bodies of the light emitting device package may be connected to each other. At this time, after manufacturing a plurality of wafer-level packages in one step, and separated into each device as described below, a plurality of light emitting device packages can be produced in a single step.

Subsequently, a lens material substrate is formed on the light emitting device package body as shown in FIG. 8C. Then, as shown in FIG. 8D, the lens material substrate is exposed to form a plurality of lenses. The lens material substrate is subjected to an exposure process to form a lens having the above-described nonuniform refractive index distribution. That is, in FIG. 8D, three lenses having a non-uniform refractive index distribution are arranged in succession. Here, when ultraviolet rays and the like are differentially irradiated onto the lens material substrate including the above-described light modulation materials such as LiNbO ₃ , a lens having a uniform refractive index distribution is provided. When ultraviolet light is irradiated to the above-described light modulation material, deformation occurs in the electron array inside the crystal, and thus deformation of the propagation path occurs when visible light, which is an electromagnetic wave, is incident. If the irradiation amount of ultraviolet rays is different, the deformation of the electron array is different depending on the distance from the center of the lens, so that the refractive index at each point of the lens can be produced differently. And, if the refractive index at the center of the lens is the largest and the refractive index is smaller toward the outside, the amount of ultraviolet irradiation will vary depending on the distance from the center of the lens. However, the specific exposure amount and the like vary depending on the refractive index of the lens to be manufactured.

As illustrated in FIG. 8E, the light emitting device package is completed through the exposure process described above, and a plurality of devices are formed together. Accordingly, each light emitting device package is completed through a separation process as shown in FIG. 8F. In the above-described process, it is apparent that the exposure of the lens material substrate may be performed before bonding with the package body. In addition, an optical layer made of air or a low refractive index film or the like may be formed between the lens and the filler, and the structure of the optical layer is as described above.

9A to 9F illustrate a second embodiment of a method of manufacturing a light emitting device package according to the present invention. The present embodiment is characterized by using an auxiliary substrate to form an optical layer.

First, the lens material substrate 330a is prepared as shown in FIG. 9A. Subsequently, an auxiliary substrate 350 is prepared as shown in FIG. 9B, in which an optical layer 340 is formed. Here, the optical layer may be formed in a dimple shape on a part of the auxiliary substrate. Then, the lens material substrate is bonded onto the auxiliary substrate as shown in Fig. 9C.

And, as shown in Figure 9d, to prepare a light emitting device package body with a light emitting device, a plurality of bodies can be connected, each body may be formed with a reflective layer and a filler.

Subsequently, the auxiliary substrate to which the lens material substrate is bonded is bonded onto the package body as shown in 9e. Then, a lens is formed as shown in FIG. 9F through the exposure process. At this time, the specific lens forming process is as described above. Then, the plurality of devices are separated to complete each light emitting device package.

Referring to the operation of the manufacturing method of the light emitting device package according to the present invention described above are as follows.

In bonding a plurality of wafer level lenses onto a wafer level package, a plurality of packages can be manufactured in one process. In addition, the optical layer may be easily formed by forming dimples on the transparent substrate. Then, after the wafer level lens is bonded to each element, a plurality of light emitting device packages can be produced in a simple process.

The present invention is not limited to the above-described embodiments, and such modifications are included in the scope of the present invention even if modifications are possible by those skilled in the art to which the present invention pertains.

The effects of the light emitting device package and the manufacturing method according to the present invention described above are as follows.

First, light efficiency may be improved by adjusting the angle of light projected to the outside of the light emitting device package.

Second, it is possible to mass-produce a light emitting device package with improved light efficiency by adjusting the angle of light projected to the outside.

Claims (15)

A filler formed on the light emitting device; And A light emitting device package formed on the filler and comprising a lens having a non-uniform refractive index distribution. The method of claim 1, wherein the refractive index of the lens, A light emitting device package characterized in that the smaller from the center of the lens toward the outside. The method of claim 1, wherein the lens, A light emitting device package comprising a disk-shaped structure. The method of claim 1, wherein the lens, A light emitting device package, characterized in that the thickness is 0.8 ~ 1.2 millimeters, the focal length is 2.0 to 3.0 millimeters. The method of claim 1, wherein the lens, A light emitting device package comprising a material selected from the group consisting of LiNbO ₃ , KTaO ₃ , KNbO ₃ , BaTiO ₃ and SrNb ₂ O ₃ . The method of claim 1, Light emitting device package further comprises a reflective layer formed on the bottom surface and / or the wall surface inside the body to which the light emitting device is fixed. According to claim 1, The lens, A light emitting device package, characterized in that the first surface in contact with the filler and / or the second surface in the opposite direction to the first surface is patterned. The method of claim 1, The light emitting device package further comprises an optical layer formed between the lens and the filler, and selectively transmits the light emitted from the light emitting device. The method of claim 8, wherein the optical layer, Light emitting device package, characterized in that made of air or low refractive index film. The method of claim 8, wherein the lens, And a first surface in contact with the optical layer and / or a second surface in a direction opposite to the first surface. Preparing a light emitting device sealed with a filler; And Exposing a lens material substrate to form a lens having a non-uniform refractive index distribution on the light emitting device. The method of claim 11, The light emitting device is provided on each of a plurality of bodies, And the lens material substrate is formed on the plurality of bodies with at least one wafer level lens substrate. The method of claim 12, Separating the plurality of body and wafer level lens substrates into one body and a lens, respectively; Each lens provided on the body has a refractive index distribution of the same method as the manufacturing method of the light emitting device. The method of claim 12, wherein the wafer level lens substrate, Method for manufacturing a light emitting device package, characterized in that the optical layer made of air or a low refractive film is formed on the surface in contact with the filler. Forming a wafer level lens substrate on a wafer level package including a plurality of light emitting devices; Exposing the wafer level lens substrate to form a plurality of lenses having a non-uniform refractive index distribution; And The wafer level package and the plurality of lenses are separated for each device to form a plurality of light emitting device package, characterized in that for forming a plurality of light emitting device package.

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