KR20110039228A - Lens mount type light emitting diode package - Google Patents

Abstract

PURPOSE: A lens mounting type light emitting diode package is provided to prevent the deterioration of the light emitting efficiency of a light emitting diode package by forming a rough surface on the light emitting surface of the LED chip. CONSTITUTION: A package body(10) comprises a recess region(12) opened on the top. A lead electrode(30) is expanded to the outside through the side of the package body. An LED chip(20) is mounted on the recess region. A lens unit(40) is spaced form the LED chip and installed on the top of the package body. A heat sink emits the heat generated from the LED chip to the outside.

Description

Lens-mounted light emitting diode package {LENS MOUNT TYPE LIGHT EMITTING DIODE PACKAGE}

The present invention relates to a light emitting diode package, and more particularly, to protect an LED chip (Light Emitting Diode chip) in the package as a mounting lens, due to the presence of an air layer (or gas layer) between the lens and the LED chip It relates to a lens-mounted light emitting diode package that can reduce the luminous efficiency degradation by improving the light emitting surface of the light emitting diode.

The light emitting diode package includes a package body and an LED chip mounted on the package body, and has advantages of small size, long life, and low power, compared to incandescent lamps, fluorescent lamps, and discharge light sources. In addition, the light emitting diode package includes an encapsulant for covering the LED chip and the bonding wire connected thereto and protecting the LED chip from external environments such as moisture.

The encapsulant completely surrounds the LED chip by molding molding, and is used for protecting the LED chip and the bonding wire and increasing the light extraction efficiency at the interface with the LED chip. To this end, the encapsulant is mainly used an epoxy material, the epoxy has a light refractive index of approximately 1.54 and the difference in light refractive index with the LED chip is relatively small compared to the air (light refractive index 1), and therefore, the light inside the LED chip It can contribute to reduce the amount of total reflection in.

However, the above-described conventional light emitting diode package was able to break the bonding wires encapsulated inside the LED chip encapsulating the LED chip, and furthermore, the heat generated from the LED chip prevents the encapsulant and the encapsulant. It causes problems such as deterioration of the sign LED chip and the bonding wire. In particular, since the process of molding the encapsulant is complicated and causes a lot of cost loss in the manufacturing process, a means for replacing an existing encapsulant used for protecting LED chips and luminous efficiency is required.

Accordingly, an object of the present invention is to solve various problems associated with the use of an existing encapsulant using a mountable lens, and at the same time, by using the mountable lens, an air layer or a gas layer existing between the mountable lens and the LED chip. It is to provide a lens-mounted light-emitting diode package that can reduce the light emission efficiency caused by improving the light exit surface of the LED chip.

In order to achieve the above object, the lens-mounted light emitting diode package according to the present invention, the package body having a recess, and is mounted on the lead electrode in the recess, but the light exit surface is formed on the rough surface of the light An LED chip having reduced total internal reflection, and a lens mounted to the package body to cover the recess spaced apart from the LED chip. Therefore, the lens can be mounted on the package body by a simple method, and is spaced apart from the LED chip at the time of mounting, thereby preventing component damage and component deterioration of the LED package. In particular, since the rough surface formed on the LED chip reduces the amount of total internal reflection within the LED chip, it is possible to suppress or reduce the luminous efficiency degradation caused by the air layer or the gas layer generated between the lens and the LED chip.

 According to an embodiment of the present invention, the lens comprises a fluorescent agent, the lens is injection molded with a resin containing the fluorescent agent, or prepared by coating the fluorescent agent on a transparent or translucent resin, glass or film Can be. In addition, the lens may include a convex portion on the front surface to narrow the directivity angle of the light emitted from the LED chip.

As described above, the present invention provides the effect that the light emitting diode package can be manufactured in a simple and inexpensive manner without a significant decrease in luminous efficiency. That is, the present invention improves the manufacturing process of a light emitting diode package using a mountable lens simply and inexpensively, and at the same time reduces the light emission efficiency of a light emitting diode package that can be caused by using the mountable lens. This can be solved by forming a rough surface on the surface.

In addition, the present invention can solve problems such as breakage and deterioration of components caused by the use of a conventional encapsulant, and can also implement light of a desired color in a simple manner by coating or mixing a fluorescent agent. In addition, when the convex portion is formed on the lens, the present invention improves the directivity of the light, so that the illumination is easy in a desired direction, which makes it suitable for local lighting in electronic devices such as mobile phones and computers.

1 is a cross-sectional view showing a lens-mounted light emitting diode package according to an embodiment of the present invention.
Figure 2 is a cross-sectional view showing a lens-mounted light emitting diode package according to another embodiment of the present invention.
3 is a schematic view of the LED chip of the light emitting diode package shown in FIG.
4A and 4B are views for explaining a principle of improving light extraction efficiency when an air layer or a gas layer forms a boundary with an LED chip;

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; The following embodiments are provided as examples to ensure that the spirit of the present invention to those skilled in the art will fully convey. Accordingly, the invention is not limited to the embodiments described below and may be embodied in other forms. And, in the drawings, the width, length, thickness, etc. of the components may be exaggerated for convenience. Like numbers refer to like elements throughout.

1 is a cross-sectional view showing a light emitting diode package according to an embodiment of the present invention.

As shown in FIG. 1, the light emitting diode package 1 of the present embodiment includes a package body 10, an LED chip 20, a lead electrode 30, and the like. The package body 10 includes a recess 12 so that the LED chip 20 can be mounted. Sidewalls of the recess 12 are formed to have a constant slope in accordance with a preferred embodiment of the present invention.

The lead electrode 30 is seated and supported on the bottom surface of the package body 10 while being composed of a cathode electrode and a cathode electrode. A portion of the lead electrode 30 is exposed in the recess 12, and a portion of the lead electrode 30 extends outside the package body 10 through the package body 10. In addition, the lead electrodes 30 extending outwardly are bent for surface mounting.

Although not shown, when the present invention is used in a power light emitting diode package that generates high temperature heat, the package body 10 may be provided with a heat sink for dissipating heat generated from the LED chip 20 to the outside. . In this case, the package body 10 may be formed by insert molding the lead electrodes 30. In the process, the heat sink may also be insert molded together.

As mentioned above, the LED chip 20 is mounted in the recess 12 of the package body 10 and electrically connected to the lead electrodes 30. In the present embodiment, the LED chip 20 is seated on one of the lead electrodes 30 to be in electrical contact, and the other lead electrode is connected to the LED chip 20 by a bonding wire.

On the other hand, the LED package 1 according to the present embodiment includes a lens 40 for protecting the LED chip 20 mounted in the recess 12 from the external environment. As shown in FIG. 1, the lens 40 is mounted on the recess 12 and is spaced apart from the LED chip 20. Accordingly, an air layer or another gas layer is formed in the recess 12 defined by the lens 40. In this embodiment, the inside of the recess 12 is filled with air or dehumidified nitrogen.

The lens 40 includes a fluorescent agent for changing the light emitted from the LED chip 20 into a light of a desired color. The lens 40 including the fluorescent agent is manufactured by injection molding a molten resin mixed with a fluorescent agent. Or it can be produced by coating a fluorescent agent on the surface of the solid glass, resin or film. Meanwhile, although the lens 40 may have a flat plate shape as shown in FIG. 1, the lens 40 may be formed in the LED package 1 according to the modified embodiment of FIGS. 2A and 2B. Likewise, it is also possible to use the lens 40 with the convex portion 42 which narrows the directing angle of the light emitted from the LED chip 20 to enable local illumination in the desired direction. In FIG. 2B, reference numeral 44 denotes a fluorescent coating layer.

As mentioned above, by attaching the lens 40, an air layer (or gas layer) is inevitably generated between the lens 40 and the LED chip 20, and the light refractive index of air is 1 as the LED chip 20. Has a large difference from the optical refractive index of. Since the total reflection critical angle is increased due to the difference in light refractive index, the light generated from the LED chip 20 does not pass through the interface between the air layer and the LED chip 20, and eventually, the light not transmitted through the interface is led to the LED chip 20. Loss of internal reflection.

3 is a view showing the above-described LED chip, showing the structure of the LED chip 20 to offset the reduction in light extraction efficiency due to the difference in light refractive index between the air layer (or gas layer) and the LED chip.

As shown in FIG. 3, the LED chip 20 according to the present embodiment includes a substrate 21, an N-type semiconductor layer 22, an active layer 23, a P-type semiconductor layer 24, and a transparent electrode layer 25. And, the electrode pad 26 is made of a structure that is laminated from the bottom toward the top. In particular, the transparent electrode layer 25 includes a light emitting surface on which the light generated by the active layer 23 is emitted. The electrode pad 26 is locally provided in a partial area on the light exit surface so as not to cover the light exit surface of the transparent electrode layer 25. In this embodiment, the substrate 21 is seated and electrically connected to one of the lead electrodes 30 shown in FIG. 1 as a conductive substrate. One end of a bonding wire is coupled to the electrode pad 26, and the other end of the bonding wire is connected to the other one of the lead electrodes 30 shown in FIG. 1. Accordingly, the LED chip 20 has a structure through which current can flow, and light is generated in the active layer 23 between the P-type semiconductor layer 24 and the N-type semiconductor layer 22.

The transparent electrode layer 25 is provided with a light exit surface, the light exit surface is formed of a rough surface (25a) consisting of a combination of LED chips, more specifically, a plurality of slopes having a predetermined slope. The rough surface 25a is formed by dry or wet etching the light exit surface. As described above, the LED chip 20 of the present embodiment has a rough surface 25a, thereby reducing the total internal reflection of light to the maximum within the total reflection critical angle determined by the difference in the refractive index of the LED chip 20 and the air. This contributes to increase the light extraction efficiency.

Although the above rough surface 25a has been described as being formed on the transparent electrode layer 25, this is an embodiment, and an LED chip (e.g., flip bonding is applied) in which a light exit surface is formed on a substrate is applied. LED chip), a rough surface may be formed on the substrate, and when the N-type semiconductor layer or the P-type semiconductor layer is exposed to the outside without a transparent electrode layer, the light exit surface of the N-type semiconductor layer or P-type semiconductor layer It is formed into a rough surface. In addition to the above-described semiconductor layers, layers such as a buffer layer and / or a current diffusion layer may be formed, and thus, detailed description thereof will be omitted since they are not directly related to the present invention.

4A and 4B are schematic diagrams for explaining and comparing the case where the rough surface 25a is formed on the light exit surface of the LED chip 20 and the case where it is not. FIG. 4A shows the light exit of the LED chip 20 '. The rough surface is not formed on the surface, and the rough surface 25a is formed on the light exit surface of the LED chip 20 in FIG. 4B. When FIG. 4a and FIG. 4b, and the total reflection critical angle (θ _c) determined as by the light refractive index difference between the air and the LED chip (20 ') and Equation 1 below, and the total reflection critical angle (θ _c) is 4a and 4b are indicated by dotted lines.

[Equation 1]

θ _c = Sin ⁻¹ (na / ns), where n _a is the refractive index of air and n _s is the refractive index of LED chip 20 and 20 '

Referring to FIG. 4A, light reaching the interface between the LED chip 20 ′ and the air layer at an angle greater than the total reflection threshold angle θ _c does not penetrate the interface and is absorbed back into the LED chip 20 ′. This absorbed light is eventually lost inside the LED chip 20 'through total internal reflection.

In contrast, referring to FIG. 4B, light reaching the interface between the LED chip 20 and the air layer at an angle greater than the total reflection threshold angle θ _c is emitted through the interface. This is possible because the exit surface of the LED chip 20 is formed as a rough surface (25a) to form an inclined surface at an angle to locally allow light transmission.

Therefore, in the case of FIG. 4A, most of the light generated from the LED chip 20 ′ does not pass through the light exit surface of the LED chip 20 ′, whereas in the case of FIG. 4B, the light is generated from the LED chip 20. Most of the light passing through the light exit surface of the LED chip 20 may be preferably transmitted to the outside through the air layer and the lens 40 thereon.

In the above description of the present embodiment, the light emitting diode package in which light is emitted to the upper portion of the package is mainly described, but the lateral emitting LED package in which light is emitted to the LED chip side is also within the scope of the present invention. Of course.

10: package body 20: LED chip
25a: rough surface 30: lead electrode
40: lens

Claims (16)

A package body having an open recess area thereon;
Disposed in the recessed area and penetrating the side of the package body to the outside.
An extended first lead electrode;
The package is disposed in the recess area spaced apart from the first lead electrode.
A second lead electrode extending through the side of the body to the outside;
An LED chip mounted in the recess region; And
A light emitting diode comprising a lens unit spaced apart from the LED chip mounted on the package body. The method according to claim 1,
The LED chip includes a first conductive semiconductor layer, an active layer and a second conductive semiconductor layer.
And a rough surface on the second conductivity-type semiconductor layer. The method according to claim 2,
Further comprising a transparent electrode layer formed on the second conductive semiconductor layer,
The rough surface is a light emitting diode, characterized in that formed on the upper surface of the transparent electrode layer. The method according to claim 2,
And an electrode pad formed on the second conductive semiconductor layer, wherein the electrode pad is formed outside the region where the rough surface is formed. The method according to claim 1,
The lens unit is characterized in that formed on the upper surface of the package body. The method according to claim 1,
It has a refractive index different from that of the lens portion between the lens portion and the LED chip.
Light emitting diodes, characterized in that filled with the material. The method of claim 6,
The material having a different refractive index is light emitting diodes, characterized in that the air. The method according to claim 1,
The lens unit includes a convex portion to correspond to a region of the upper surface of the LED chip.
Light emitting diodes, characterized in that. The method according to claim 1,
The lens unit comprises a phosphor. The method according to claim 9,
The lens unit comprises a resin containing the phosphor. The method according to claim 9,
Light emitting diodes, characterized in that the air filled between the lens unit and the LED chip. The light emitting diode according to any one of claims 1 to 11, wherein an upper surface of the lens portion and an upper surface of the package body are coplanar at least near the boundary between the lens portion and the package body. The light emitting diode according to any one of claims 1 to 11, wherein the first lead terminal and the second lead terminal each include end portions extending in a direction away from the package body by a bent structure. The light emitting diode of claim 13, wherein the lower surface of the distal end and the lower surface of the package body are on a same plane. The light emitting diode according to any one of claims 1 to 11, wherein a phosphor is formed below the lens unit. The method of claim 14, wherein the phosphor is formed in the form of a layer on the lower portion of the lens unit
Light emitting diodes characterized in that.

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