KR20160071837A

KR20160071837A - Light emitting device package, backlight unit and lighting device

Info

Publication number: KR20160071837A
Application number: KR1020140179510A
Authority: KR
Inventors: 오승현; 김평국; 한강민
Original assignee: 주식회사 루멘스
Priority date: 2014-12-12
Filing date: 2014-12-12
Publication date: 2016-06-22

Abstract

The present invention relates to a light emitting element package, a backlight unit, and a lighting device which can be used for a display or a lighting. The light emitting element package comprises: a substrate having a first electrode installed in one side and a second electrode formed in the other side based on an electrode separation line; and a light emitting element mounted on a mounting surface of the substrate. The substrate includes at least one through-hole unit adjacent to the mounting surface of the substrate to buffer heat expansion of the light emitting element and the substrate generated when the light emitting element emits light.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device package, a backlight unit,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device package, a backlight unit, and a lighting device, and more particularly, to a light emitting device package, a backlight unit, and a lighting device.

A light emitting diode (LED) is a kind of semiconductor device that can emit light of various colors by forming a light emitting source through the formation of a PN diode of a compound semiconductor. Such a light emitting device has a long lifetime, can be reduced in size and weight, and can be driven at a low voltage. In addition, these LEDs are resistant to shock and vibration, do not require preheating time and complicated driving, can be packaged after being mounted on a substrate or lead frame in various forms, so that they can be modularized for various purposes and used as a backlight unit A lighting device, and the like.

The conventional light emitting device package may include a light emitting device and a substrate for supporting the light emitting device.

However, in such a conventional light emitting device package, the light emitting device having different materials and the substrate are thermally expanded by different forces due to the high-temperature environment during reflow or by the high-temperature heat generated in the light emitting device, A popping phenomenon in which the medium or the light emitting element is broken or a tilt phenomenon in which the light emitting axis of the light emitting element is twisted or a bonding deviation phenomenon is generated and the appearance is bad, Various problems such as abnormal operation or increased heat resistance have occurred.

The defective bonding phenomenon due to the difference of materials is caused not only in the case where the substrate is a lead frame but also in a multi-layer substrate composed of a multilayer. Since the thermal expansion force between the layers constituting the substrate is different, .

Disclosure of Invention Technical Problem [8] Accordingly, the present invention has been made to solve the above problems, and it is an object of the present invention to provide a light emitting device having a relatively small thermal expansion force and a through- a tilt phenomenon in which a light emitting axis is twisted, a bonding deviation phenomenon, and the like, and a backlight unit and a lighting apparatus. However, these problems are exemplary and do not limit the scope of the present invention.

According to an aspect of the present invention, there is provided a light emitting device package comprising: a substrate having a first electrode on one side and a second electrode on the other side of the electrode separation line; And a light emitting element mounted on a seating surface of the substrate, wherein the substrate is provided with a light emitting element and a light emitting element which are located near the seating surface of the substrate so as to buffer the thermal expansion of the light emitting element and the substrate, And one through hole may be formed.

According to an aspect of the present invention, the substrate further includes: an upper electrode layer including the first electrode and the second electrode; A substrate core layer formed on a lower surface of the upper electrode layer and supporting the upper electrode layer; And a lower electrode layer formed on a lower surface of the substrate core layer and electrically connected to the upper electrode layer, wherein the through hole portion is formed on the upper electrode layer and the substrate core layer, have.

According to an aspect of the present invention, the through hole portion is formed to have a length larger than at least the length of the seating surface in the lateral direction of the seating surface opposite to the electrode dividing line, and the light emitting device is a flip- .

According to an aspect of the present invention, the through hole portion may be formed by selecting at least one of a round rectangular shape, an elliptical shape, a rectangular shape, a zigzag shape, an oblique shape, a curved shape, a polygonal shape, and a combination thereof at least at both ends.

The light emitting device package according to the present invention may further include a guide dam part formed on at least a part of the seating surface and / or the through hole part and having an insulating material for aligning the position of the light emitting device or the bonding medium .

According to an aspect of the present invention, the guide dam may be formed in a rectangular shape as a whole on the first electrode and the second electrode across the electrode separation line.

According to an aspect of the present invention, the substrate may be a lead frame.

According to another aspect of the present invention, there is provided a backlight unit comprising: a substrate having a first electrode on one side and a second electrode on the other side of an electrode separation line; A light emitting element mounted on a seating surface of the substrate; And a light guide plate provided on an optical path of the light emitting device, wherein the substrate includes at least one light emitting element and at least one light emitting element adjacent to the seating surface of the substrate for buffering thermal expansion of the light emitting element and the substrate, The through hole portion of the first through-hole is formed.

According to an aspect of the present invention, there is provided a lighting apparatus comprising: a substrate having a first electrode on one side and a second electrode on the other side of an electrode separation line; And a light emitting device mounted on a seating surface of the substrate, wherein the substrate includes at least one light emitting device and at least one light emitting device formed on the mounting surface of the substrate so as to buffer the thermal expansion of the light emitting device and the substrate, The through hole portion of the first through-hole is formed.

According to some embodiments of the present invention as described above, the popping phenomenon, the tilt phenomenon in which the light emitting axis is turned off, the bonding deviation phenomenon, and the like are prevented, Operation, and heat resistance can be prevented. It is possible to produce high quality products with high efficiency, ultra low price and high reliability by stabilizing the flip chip processor, and to increase the product yield and to reduce the product cost . Of course, the scope of the present invention is not limited by these effects.

1 is an exploded perspective view of a light emitting device package according to some embodiments of the present invention.
2 is a plan view showing a through hole portion of the light emitting device package of FIG.
3 is a cross-sectional view of the light emitting device package of FIG.
4 to 6 are plan views showing various embodiments of the through hole portion of the light emitting device package of FIG.
FIG. 7 is a plan view showing a light emitting device package according to some other embodiments of the present invention. FIG.
8 is a cross-sectional view of the light emitting device package of Fig.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified into various other forms, It is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more thorough and complete, and will fully convey the concept of the invention to those skilled in the art. In the drawings, the thickness and size of each layer are exaggerated for convenience and clarity of explanation.

It is to be understood that throughout the specification, when an element such as a film, region or substrate is referred to as being "on", "connected to", "laminated" or "coupled to" another element, It will be appreciated that elements may be directly "on", "connected", "laminated" or "coupled" to another element, or there may be other elements intervening therebetween. On the other hand, when one element is referred to as being "directly on", "directly connected", or "directly coupled" to another element, it is interpreted that there are no other components intervening therebetween do. Like numbers refer to like elements. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items.

Although the terms first, second, etc. are used herein to describe various elements, components, regions, layers and / or portions, these members, components, regions, layers and / It is obvious that no. These terms are only used to distinguish one member, component, region, layer or section from another region, layer or section. Thus, a first member, component, region, layer or section described below may refer to a second member, component, region, layer or section without departing from the teachings of the present invention.

Also, relative terms such as "top" or "above" and "under" or "below" can be used herein to describe the relationship of certain elements to other elements as illustrated in the Figures. Relative terms are intended to include different orientations of the device in addition to those depicted in the Figures. For example, if the element is inverted in the figures, the elements depicted as being on the upper surface of the other elements will have a direction on the lower surface of the other elements. Thus, the example "top" may include both "under" and "top" directions depending on the particular orientation of the figure. If the elements are oriented in different directions (rotated 90 degrees with respect to the other direction), the relative descriptions used herein can be interpreted accordingly.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, " comprise "and / or" comprising "when used herein should be interpreted as specifying the presence of stated shapes, numbers, steps, operations, elements, elements, and / And does not preclude the presence or addition of one or more other features, integers, operations, elements, elements, and / or groups.

Hereinafter, embodiments of the present invention will be described with reference to the drawings schematically showing ideal embodiments of the present invention. In the figures, for example, variations in the shape shown may be expected, depending on manufacturing techniques and / or tolerances. Accordingly, the embodiments of the present invention should not be construed as limited to the particular shapes of the regions illustrated herein, but should include, for example, changes in shape resulting from manufacturing.

1 is a partially exploded perspective view of a light emitting device package 100 according to some embodiments of the present invention. 2 is a plan view showing a through hole portion H of the light emitting device package 100 of FIG. 1, and FIG. 3 is a sectional view of the light emitting device package 100 of FIG.

1 to 3, the light emitting device package 100 according to some embodiments of the present invention may include a substrate 10 and a light emitting device 20. Referring to FIG.

For example, in the substrate 10, the first electrode 11 is provided on one side of the electrode separation line SL, the second electrode 12 is formed on the other side, and the epoxy resin sheet is formed into a multi- A printed circuit board (PCB) or a flexible printed circuit board (FPCB) made of a soft material.

More specifically, for example, as shown in FIGS. 1 to 3, the substrate 10 has suitable mechanical strength and insulation property to support or accommodate the light emitting device 20, An upper electrode layer 10-1 including the electrode 11 and the second electrode 12 and an insulating layer 10-1 formed on the lower surface of the upper electrode layer 10-1 and supporting the upper electrode layer 10-1, And a lower electrode layer 10-3 formed on a lower surface of the substrate core layer 10-2 and capable of being electrically connected to the upper electrode layer 10-1 .

For example, the upper electrode layer 10-1 and the lower electrode layer 10-3 of the substrate 10 may be formed of a metal material such as aluminum, copper, zinc, tin, lead, gold, or silver .

(Ag), a silver (Ag) alloy, a silver (Ag) alloy layer, an aluminum (Al), an aluminum (Ag) alloy layer having excellent reflectivity on its surface so as to maximize the reflectivity (Al) alloy, an Al alloy layer, a Cu alloy, a Cu alloy layer, a Cu alloy layer, a Pt alloy, a Pt alloy, a Pt alloy, (Au), a gold (Au) plated layer, a gold (Au) alloy layer, palladium (Pd), ruthenium (Ru), rhodium (Rh), and combinations thereof. .

As the substrate core layer 10-2, an insulator such as an epoxy resin, a resin, a glass, an epoxy, and a ceramic may be used.

In order to improve workability, the substrate 10 may be formed by partially or wholly selecting at least one of EMC (Epoxy Mold Compound), PI (polyimide), ceramic, graphene, glass synthetic fiber, Lt; / RTI >

More specifically, for example, the upper electrode layer 10-1 of the substrate 10 may buffer the thermal expansion of the light emitting device 20 and the substrate 10, which are generated when the light emitting device 20 emits light. At least one through hole (H) may be formed near the seating surface (F) of the substrate (10).

2, the through-hole portion H may be formed on the side of the seating surface F opposite to the electrode separation line SL so as to protect the seating surface F from thermal expansion in the lateral direction. (L2) larger than the length (L1) of the seating surface (F) in the lateral direction.

However, the length, shape, number, and the like of the through hole portion H are not limited to the drawings, and various shapes, shapes, numbers, and the like can be formed.

1 to 3, the through hole portion H may be formed to reduce the volume of the upper electrode layer 10-1 and the substrate core layer 10-2 to reduce the thermal expansion force, May be formed from the upper electrode layer 10-1 to the substrate core layer 10-2.

However, the through hole portion H is not limited to the drawings, and the volume of the upper electrode layer 10-1, the substrate core layer 10-2, and the lower electrode layer 10-3 may be reduced, The through hole portion H may be formed from the upper electrode layer 10-1 to the lower electrode layer 10-3 through the substrate core layer 10-2.

The substrate 10 is not necessarily limited to the above-described printed circuit board or flexible printed circuit board, but may be a lead frame made of a single metal panel.

That is, although not shown, the through-hole portion H may be formed in the same configuration on the substrate of the lead frame type and may play the same role.

Therefore, the thermal expansion force applied to the seating surface F by the through hole portion H can be reduced, and even if the thermal expansion force is applied, the shape of the through hole portion H is deformed, The difference between the thermal expansion force of the light emitting element 20 applied to the seating surface F and the thermal expansion force of the substrate 10 can be alleviated.

1 to 3, the light emitting device 20 is mounted on a seating surface F of the substrate 10, and a flip chip type LED having a pad P on a bottom surface thereof Lt; / RTI >

More specifically, for example, the light emitting device 20 may be made of a semiconductor. For example, LEDs of blue, green, red, and yellow light emission, LEDs of ultraviolet light emission, and LEDs of infrared light emission, which are made of a nitride semiconductor, can be applied.

In addition, the light emitting device 20 may be a flip chip type LED. However, the light emitting device 20 is not limited to a flip chip type LED, and a horizontal or vertical type LED may be applied.

In the case where the light emitting device 20 is a horizontal or vertical type LED, the through hole portion H described above may be formed around the seating surface on which the light emitting device 20 is mounted.

The light emitting device 20 can be formed by epitaxially growing nitride semiconductors such as InN, AlN, InGaN, AlGaN, and InGaAlN on a sapphire substrate for growth or a silicon carbide substrate by a vapor phase growth method such as MOCVD To grow. The light emitting device 20 may be formed using semiconductors such as ZnO, ZnS, ZnSe, SiC, GaP, GaAlAs, and AlInGaP in addition to the nitride semiconductor. These semiconductors can be stacked in the order of an n-type semiconductor layer, a light emitting layer, and a p-type semiconductor layer. The light emitting layer (active layer) may be a laminated semiconductor having a multiple quantum well structure or a single quantum well structure or a laminated semiconductor having a double hetero structure. In addition, the light emitting device 20 can be selected to have an arbitrary wavelength depending on the application such as display use and illumination use.

Here, as the growth substrate, an insulating, conductive or semiconductor substrate may be used if necessary. For example, the growth substrate may be sapphire, SiC, Si, MgAl ₂ O ₄ , MgO, LiAlO ₂ , LiGaO ₂ , GaN. A GaN substrate, which is a homogeneous substrate, is preferable for epitaxial growth of a GaN material, but a GaN substrate has a problem of high production cost due to its difficulty in manufacturing.

Sapphire and silicon carbide (SiC) substrates are mainly used as the different substrates. Sapphire substrates are more utilized than expensive silicon carbide substrates. When using a heterogeneous substrate, defects such as dislocation are increased due to the difference in lattice constant between the substrate material and the thin film material. Also, due to the difference in the thermal expansion coefficient between the substrate material and the thin film material, warping occurs at a temperature change, and warping causes a crack in the thin film. This problem may be reduced by using a buffer layer between the substrate and the GaN-based light emitting laminate.

In addition, the substrate for growth may be completely or partially removed or patterned in order to improve the optical or electrical characteristics of the LED chip before or after the growth of the LED structure.

For example, in the case of a sapphire substrate, the substrate can be separated by irradiating the laser to the interface with the semiconductor layer through the substrate, and the silicon or silicon carbide substrate can be removed by a method such as polishing / etching.

Another supporting substrate may be used for removing the growth substrate. In order to improve the light efficiency of the LED chip on the opposite side of the growth substrate, the supporting substrate may be bonded using a reflective metal, As shown in FIG.

In addition, patterning of the growth substrate improves the light extraction efficiency by forming irregularities or slopes before or after the LED structure growth on the main surface (front surface or both sides) or side surfaces of the substrate. The size of the pattern can be selected from the range of 5 nm to 500 μm and it is possible to make a structure for improving the light extraction efficiency with a rule or an irregular pattern. Various shapes such as a shape, a column, a mountain, a hemisphere, and a polygon can be adopted.

In the case of the sapphire substrate, the crystals having a hexagonal-rhombo-cubic (Hexa-Rhombo R3c) symmetry have lattice constants of 13.001 and 4.758 in the c-axis direction and the a-axis direction, respectively, and have C plane, A plane and R plane. In this case, the C-plane is relatively easy to grow the nitride film, and is stable at high temperature, and thus is mainly used as a substrate for nitride growth.

Another material of the growth substrate is a Si substrate, which is more suitable for large-scale curing and relatively low in cost, so that mass productivity can be improved.

Since the external quantum efficiency of the light emitting device is lowered by absorbing light generated from the GaN-based semiconductor, the Si (silicon) substrate may be removed, if necessary, and Si, Ge, SiAl, Or a support substrate such as a metal substrate is further formed and used.

When a GaN thin film is grown on a different substrate such as the Si substrate, the dislocation density increases due to the lattice constant mismatch between the substrate material and the thin film material, and cracks and warpage Lt; / RTI > The buffer layer may be disposed between the growth substrate and the light emitting stack for the purpose of preventing dislocation and cracking of the light emitting stack. The buffer layer also functions to reduce the scattering of the wavelength of the wafer by adjusting the degree of warping of the substrate during the growth of the active layer.

The buffer layer may be made of GaN, AlN, AlGaN, InGaN, or InGaNAlN. If necessary, a material such as ZrB ₂ , HfB ₂ , ZrN, HfN, or TiN may be used. Further, a plurality of layers may be combined, or the composition may be gradually changed.

Meanwhile, as shown in FIGS. 1 to 3, one light emitting device 20 may be mounted on the substrate 10, and a plurality of light emitting devices may be mounted thereon.

2, the operation of the light emitting device package 100 according to some embodiments of the present invention will be described. After the bonding medium B is bonded, When the environment is formed or power is applied to the light emitting device 20 and the high temperature heat from the light emitting device 20 is transferred to the substrate 10, the light emitting device 20 having a relatively low thermal expansion coefficient The thermal expansion force F1 of the upper electrode layer 10-1 of the substrate 10, which is a metal material having a relatively high thermal expansion coefficient, can act.

The thermal expansion force F1 may accumulate in the left and right directions at the upper and lower ends of the substrate 10, on which the separation trench 10b is not formed, based on the electrode separation line SL.

However, on the seating surface F on which the through hole portion H is formed, the substrate 10 is cut in the left and right direction and can be dispersed and acted on the separated small forces F2 and F3.

Therefore, the through hole portion H is formed in the vicinity of the seating surface F of the substrate 10 to be bonded to the light emitting device 20 having a relatively small thermal expansion force, thereby alleviating the difference in thermal expansion force, popping phenomenon, a tilt phenomenon in which the light emitting axis is turned, and a bonding deviation phenomenon can be prevented.

4 to 6 are plan views showing various embodiments of the through hole portion H of the light emitting device package 100 of FIG.

4 to 6, the through hole portion H is not limited to the rounded square H1 at both ends in FIGS. 1 to 3, but may be an ellipse H2 in FIG. 4, (H3) of FIG. 6, a zigzag shape (H4) of FIG. 6, and the like, an oblique shape, a curved shape, a polygon, and various geometric shapes can be applied.

When the width of the through hole portion H is limited, the square H3 of FIG. 5 can remove the maximum volume, but since cracks may occur at the corner portions, the both ends of FIG. The quadrangle H1 or the ellipse H2 in Fig. 4 may be advantageous. In addition, the length may be longer than the straight line 10c-1. In addition, the staggered shape H4 of Fig. 6 can prolong the length to actively accommodate thermal deformation.

By optimizing the shapes of the through holes H so as to increase the thermal and mechanical buffer effect by making use of advantages and disadvantages according to the shape, and to reduce the manufacturing cost and the manufacturing time, the shape of the through holes H can be designed.

FIG. 7 is a plan view showing a light emitting device package 200 according to some other embodiments of the present invention, and FIG. 8 is a sectional view of the light emitting device package 200 of FIG.

7 and 8, the light emitting device package 200 according to some other embodiments of the present invention is formed on at least a part of the seating surface F and / or the through hole portion H And a guide dam portion G for insulating the light emitting device 20 or the bonding medium B from each other.

7 and 8, the guide dam G is disposed between the first electrode 11 and the second electrode 12 across the electrode separation line SL, It may be formed in a rectangular band shape as a whole.

Accordingly, when the light emitting device 20 is mounted using the guide dam G, the light emitting device 20 or the bonding medium B can be aligned to accurately align the light emitting axes.

Although not shown, the light emitting device package 100 according to some embodiments of the present invention may include various reflective members, sealing members, transparent members, and the like in addition to the substrate 10 and the light emitting device 20 described above. A light conversion material such as an encapsulant, a fluorescent material or a quantum dot, a lens layer, and the like.

3, the backlight unit 1000 according to some embodiments of the present invention includes a first electrode 11 on one side with respect to an electrode separation line SL, A light emitting device 20 mounted on a seating surface F of the substrate 10 and a light guide plate 110 installed on an optical path of the light emitting device 20, And the substrate 10 is mounted on the seating surface F of the substrate 10 so as to buffer the thermal expansion of the light emitting device 20 and the substrate 10 generated when the light emitting device 20 emits light. And at least one through hole (H) is formed in the vicinity of the through hole (H).

Herein, the substrate 10 and the light emitting device 20 are the same as those of the light emitting device package 100 according to various embodiments of the present invention shown in FIGS. 1 to 8, And roles may be the same. Therefore, detailed description is omitted.

In addition, the light guide plate 110 may be an optical member that can be made of a light-transmitting material to guide light converted from the light emitting device 20.

The light guide plate 110 may be installed in an optical path of the light generated by the light emitting device 20 and may be transmitted over a wider area.

The light guide plate 110 may be made of polycarbonate, polysulfone, polyacrylate, polystyrene, polyvinyl chloride, polyvinyl alcohol, polynorbornene, polyester, or the like , And various light transmitting resin materials may be applied. In addition, the light guide plate 110 may be formed by various methods such as forming fine patterns, fine protrusions, diffusion films, or the like on the surface, or forming fine bubbles therein.

Although not shown, various diffusion sheets, prism sheets, filters, and the like may be additionally provided above the light guide plate 110. In addition, various display panels such as an LCD panel may be installed above the light guide plate 110. [

Meanwhile, although not shown, the present invention may include a lighting device or a display device including the above-described light emitting device package 100 (200). Here, the components of the illumination device or the display device according to some embodiments of the present invention may have the same configuration and function as those of the above-described light emitting device package of the present invention. Therefore, detailed description is omitted.

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the invention. Accordingly, the true scope of the present invention should be determined by the technical idea of the appended claims.

10: substrate
11: first electrode
12: Second electrode
H: Through hole part
H1: Rounded square with both ends
H2: Oval
H3: Rectangle
H4: Zigzag type
L1, L2: Length
10-1: upper electrode layer
10-2: substrate core layer
10-3: Lower electrode layer
SL: Electrode separation line
F: Seat face
20: Light emitting element
P: Pad
B: bonding medium
G: Guide dam
100: Light emitting device package
110: light guide plate
1000: Backlight unit

Claims

A substrate having a first electrode on one side and a second electrode on the other side of the electrode separation line; And
A light emitting element mounted on a seating surface of the substrate;
Lt; / RTI >
Wherein:
Wherein at least one through hole is formed in the vicinity of the seating surface of the substrate so as to buffer thermal expansion of the light emitting device and the substrate when the light emitting device emits light.

The method according to claim 1,
Wherein:
An upper electrode layer including the first electrode and the second electrode;
A substrate core layer formed on a lower surface of the upper electrode layer and supporting the upper electrode layer; And
A lower electrode layer formed on a lower surface of the substrate core layer and electrically connected to the upper electrode layer;
Or a FPCB substrate,
And the through hole portion is formed in the upper electrode layer and the substrate core layer.

The method according to claim 1,
Wherein the through hole portion is formed to have a length larger than a length of the seating surface in the lateral direction of the seating surface opposite to the electrode dividing line,
Wherein the light emitting element is a flip chip type LED.

The method according to claim 1,
Wherein the through hole portion is formed by selecting at least one of a rectangular, oval, rectangular, zigzag, oblique, curved, polygonal, and combinations thereof at least at both ends.

The method according to claim 1,
A guide dam portion formed on at least a part of the seating surface and / or the through hole portion and having an insulating material for aligning the position of the light emitting device or the bonding medium;
Emitting device package.

6. The method of claim 5,
Wherein the guide dam portion is formed in a rectangular shape as a whole on the first electrode and the second electrode across the electrode separation line.

The method according to claim 1,
Wherein the substrate is a lead frame.

A substrate having a first electrode on one side and a second electrode on the other side of the electrode separation line;
A light emitting element mounted on a seating surface of the substrate; And
A light guide plate installed in an optical path of the light emitting device;
Lt; / RTI >
Wherein:
Wherein at least one through hole is formed in the vicinity of a seating surface of the substrate so as to buffer thermal expansion of the light emitting device and the substrate when the light emitting device emits light.

A substrate having a first electrode on one side and a second electrode on the other side of the electrode separation line; And
A light emitting element mounted on a seating surface of the substrate;
Lt; / RTI >
Wherein:
Wherein at least one through hole is formed in the vicinity of a seating surface of the substrate so as to buffer thermal expansion of the light emitting device and the substrate when the light emitting device emits light.