KR20110132729A - Backlight unit having leds and method for manufacturing the same - Google Patents

Abstract

PURPOSE: A backlight unit including an LED and a manufacturing method thereof are provided to improve a heat radiation property by directly transmitting heat to a BLU chassis body made of thermally conductive metal materials. CONSTITUTION: A backlight unit includes a BLU(Back Light Unit) chassis, a flexible PCB(Printed Circuit Board), and one or more LED packages(103). The flexible PCB is formed on the BLU chassis. One or more LED packages are bonded with the flexible PCB.

Description

Backlight unit having LED and method of manufacturing the same {Backlight Unit having LEDs and Method for manufacturing the same}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight unit for a liquid crystal display device having a light emitting diode (LED) and a method of manufacturing the same. In particular, the heat dissipation characteristics are improved while reducing components for dissipating heat generated from the LED. The present invention relates to a backlight unit having a simplified manufacturing process and a method of manufacturing the same.

Light Emitting Diode (LED) is a well-known semiconductor light emitting device that converts electric current into light. Starting with the commercialization of red LEDs using GaAsP compound semiconductors, GaP: N series green LEDs, including information and communication devices, It has been used as a light source for display images of electronic devices.

Gallium nitride compound semiconductors (Gallium Nitride: GaN) have high thermal stability and a wide bandgap (0.8 to 6.2 eV), which has attracted much attention in the development of high-power electronic components including LEDs. One reason for this is that GaN can be combined with other elements (indium (In), aluminum (Al), etc.) to produce semiconductor layers that emit green, blue and white light. Since white light can be emitted, it can be used for illumination, and one example thereof is used for a backlight unit of a liquid crystal display device.

Background Art In recent years, in accordance with the trend of thinning and high performance of image display devices, liquid crystal displays have been widely used in TVs and monitors. Since the liquid crystal panel does not emit light by itself, the liquid crystal display requires a separate backlight unit (also referred to simply as 'BLU').

BLU using conventional CCFL (cold cathode fluorescent lamp) has disadvantages such as environmental pollution due to mercury, slow response speed, and difficulty in implementing partial driving. To overcome this problem, LED is proposed as a BLU light source instead of CCFL. BLU using these LEDs can realize high color reproducibility, environment-friendly, and local dimming driving.

In order to be used as a backlight unit of the liquid crystal display device, a plurality of white LEDs may be disposed on a substrate, and the light emitted from the white LEDs may be uniformly diffused.

BLU using LED is divided into direct type BLU (direct type) and edge type BLU (side type). In the direct type, a surface light source using LEDs is disposed under the liquid crystal panel, and in the edge type, a bar-shaped light source having an LED is located on the side of the liquid crystal panel. Light is irradiated toward the liquid crystal panel through the light guide plate.

1 is an exemplary view of a backlight unit having a LED according to the prior art.

According to the related art, the heat sink 102 is provided on the BLU chassis 101, and the LED package 103 is formed after the thermal pad 104 and the metal PCB 105 are sequentially formed on the heat sink 102. Will be mounted.

That is, the insulating layer included in the metal PCB 105 together with the thermal pad 104 is composed of a material having low thermal conductivity, and thus has a problem of acting as a factor that inhibits heat dissipation.

In addition, the heat dissipation plate 102 is usually formed to a thickness of 0.2 mm or less. In this case, it is difficult to form a flexible backlight unit because mechanical bending is difficult.

Accordingly, there is a demand for a backlight unit having an LED and a backlight unit capable of forming various types of BLU using a flexible material while improving heat dissipation characteristics while reducing the number of components in the heat dissipation structure.

The present invention has been made to solve the above-mentioned problems of the prior art, to provide a backlight unit having a LED and a method of manufacturing the same, which has improved heat dissipation characteristics while reducing the number and type of components that enter the heat dissipation structure. There is this.

Another object of the present invention is to provide a backlight unit having a LED capable of forming various types of backlight units regardless of the shape of a BLU chassis by using a flexible material in forming a heat dissipation structure, and a method of manufacturing the same. .

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the description of the present invention. .

According to an aspect of the present invention to solve the above problems of the prior art, BLU (Back Light Unit) chassis (Chassis); A flexible printed circuit board (PCB) formed on the BLU chassis; And at least one LED package bonded onto the flexible PCB.

In the present invention, the flexible PCB, the insulating film; An electrical wiring layer formed on the insulating film; An insulating layer formed on the electrical wiring layer; And a cover layer formed on the insulating layer.

In the present invention, the insulating layer and the cover layer includes a backlight unit having an LED, characterized in that formed using polyimide (polyimide).

In the present invention, the insulating film is formed using any one or more materials selected from rosin-based flux, phenol, epoxy, polyimide, or teflon resin. It includes a backlight unit having an LED, characterized in that.

The thickness of the insulating film in the present invention includes a backlight unit having an LED, characterized in that 10um to 50um.

In the present invention, the thickness of the flexible PCB includes a backlight unit having an LED, characterized in that 0.035 mm to 0.5 mm.

In the present invention, the junction between the flexible PCB and the LED package is to remove a predetermined region of the cover layer and the insulating layer of the flexible PCB, and to mount the LED package on the electrical wiring layer to which the predetermined region is removed and exposed. And a backlight unit having an LED.

In the present invention, the LED package and the electrical wiring layer includes a backlight unit having an LED, characterized in that bonded using a lead frame SMD (Surfice Mounted Device) pad and SMD solder.

In the present invention, the height (H) from the SMD solder to the upper surface of the LED package includes a backlight unit having an LED, characterized in that greater than the thickness (h) of the cover layer and the insulating layer.

In the present invention includes a backlight unit having an LED, characterized in that formed to have at least two holes (hole) between the LED package and the electrical wiring layer.

In the present invention, a backlight unit having an LED having a short insulating layer for electrically shorting an electrical wiring layer in a lower region of the hole, wherein the electrical wiring layers are spaced apart from each other. It includes.

The present invention is formed by bonding to both sides of the LED package and the upper surface of the cover layer, the flexible part to bend the flexible PCB so as to be formed spaced apart from the air gap (air gap) at the BLU shot time. It includes a backlight unit having an LED, characterized in that it comprises a.

According to another aspect of the present invention for solving the above-described problems of the prior art, forming a flexible PCB on the BLU chassis; Removing a cover layer and an insulating layer on a predetermined region on the flexible PCB; And mounting at least one LED package on the electrical wiring layer of the flexible PCB to which the cover layer and the insulating layer are removed and exposed.

The mounting of the LED package may include forming at least two holes in a predetermined area of an electrical wiring layer of the flexible PCB to which the cover layer and the insulating layer are removed and exposed; Forming a short insulating layer in the hole; And bonding the LED package by using a lead frame SMD mounted pad (SMD) pad and SMD solder so that at least two holes are formed between the short-circuit insulating layer and the LED package. It includes a method of manufacturing a backlight unit.

By the backlight unit having the LED of the present invention, since heat-resistant parts are eliminated and heat is directly transferred to the BLU chassis main body made of a high thermal conductivity metal material, heat dissipation characteristics are much better than before.

In addition, the type and number of components in the heat dissipation structure can be reduced, so that the thickness of the backlight unit can be manufactured thinly, and the manufacturing process of the backlight unit having the LED with a greatly simplified manufacturing process and reduced manufacturing cost is provided. There is.

In addition, according to the present invention, by forming a backlight unit using a flexible PCB, there is an effect of providing a backlight unit having a LED capable of forming various types of backlight unit irrespective of the shape of the BLU chassis and a method of manufacturing the same. .

1 is an illustration of a backlight unit having an LED according to the prior art.
2a to 2b is a block diagram of a backlight unit having an LED according to an embodiment of the present invention.
3A to 3F are exemplary views showing step-by-step manufacturing procedures of a backlight unit having an LED according to an embodiment of the present invention.
4A is an exemplary view of a backlight unit having a plurality of LEDs according to an embodiment of the present invention.
4B is a side view of a backlight unit having an LED according to an embodiment of the present invention.
5A is a plan view of a backlight unit having an LED including a bent portion according to an embodiment of the present invention.
5B is an illustration of a backlight unit having an LED including a bent portion according to another embodiment of the present invention.
6 is a flow chart of a method for manufacturing a backlight unit having an LED according to an embodiment of the present invention.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Prior to this, terms or words used in the specification and claims should not be construed as having a conventional or dictionary meaning, and the inventors should properly explain the concept of terms in order to best explain their own invention. Based on the principle that can be defined, it should be interpreted as meaning and concept corresponding to the technical idea of the present invention. Therefore, the embodiments described in this specification and the configurations shown in the drawings are merely the most preferred embodiments of the present invention and do not represent all the technical ideas of the present invention. Therefore, It is to be understood that equivalents and modifications are possible.

1 is an exemplary view of a backlight unit having an LED according to the prior art.

According to the related art, the heat sink 102 is provided on the BLU chassis 101, and the LED package 103 is formed after the thermal pad 104 and the metal PCB 105 are sequentially formed on the heat sink 102. Will be mounted.

Typically, the thermal pad 104 is formed of a material having a thermal conductivity of 0.6w / m ?? k to 0.9w / m ?? k, and the metal PCB 105 is formed of an aluminum layer, an insulating layer, and a copper layer. In general, the insulating layer is formed of a material having a thermal conductivity of 1.5 w / m ?? k to 2.0 w / m ?? k.

Therefore, since the thermal pad 104 and the insulating layer are formed of a material having low thermal conductivity, the thermal pad 104 and the insulating layer have a problem of being an inhibitor in dissipating heat from the LED package.

In addition, according to the prior art, the heat dissipation plate 102 is usually formed to a thickness of 0.2 mm or less. In this case, there is a problem in that a flexible backlight unit is difficult to form due to difficulty in mechanical bending.

2A to 2B are diagrams illustrating a backlight unit having an LED according to an embodiment of the present invention.

According to the backlight unit provided with the LED of the present invention, a BLU chassis 101; A flexible PCB 109 formed on the BLU chassis; And at least one LED package 103 formed on the flexible PCB.

The BLU sash 101 may be formed using a metal material, and particularly, may be formed of aluminum or an aluminum-based alloy. In addition, according to the needs of the invention, the BLU chassis may have a separate insulating film (not shown) on its upper surface.

Unlike the conventional PCB, the flexible PCB 102 may be formed using a known flexible material that is free to bend, and the insulating film 116, the electrical wiring layer 115, the insulating layer 112, and the cover layer 111 may be formed. It may be formed by depositing sequentially.

The insulating layer 112 and the cover layer 111 are preferably formed using polyimide, but are not necessarily limited thereto, and may be formed of a known material such as FR4 or photo solder resist. It may be formed.

The insulating layer 116 is formed using one or more materials selected from rosin-based flux, phenol, epoxy, polyimide, or teflon resin. can do.

It is preferable that the thickness of the insulating film 116 is 10um to 50um.

The electrical wiring layer 115 is preferably formed of copper (Cu) or aluminum (Al), but is not limited thereto. Any material may be used as long as it is a metallic material capable of electrical conductivity.

The thickness of the flexible PCB 109 is preferably 0.035 mm to 0.5 mm, to facilitate mechanical bending.

The junction between the flexible PCB 109 and the LED package 103 may include a predetermined region of the cover layer 111 and the insulating layer 112 of the flexible PCB, and the predetermined region may be removed to expose the electrical wiring layer ( The LED package 103 may be mounted on 115.

The LED package 103 and the electrical wiring layer 115 may be bonded using a leadframe SMD (Surfice Mounted Device) pad 120 and a SMD solder 121. As described above, when the LED package 103 having the lead frame SMD pad 120 is mounted on the electrical wiring layer 115 by the soldering method, the thermal conductivity is different from that of the conventional thermal pad or metal PCB. It is much better because it has better heat dissipation effect.

The height (H) 123 from the SMD solder 121 to the top surface of the LED package 103 is preferably greater than the thickness (h) 124 of the cover layer and the insulating layer. This is because the LED package 103 should be formed higher than the cover layer to facilitate formation of the bent portion to be described later.

Preferably, at least two holes 103 are formed between the LED package 103 and the electrical wiring layer 115, and a short insulating layer 117 is formed in the lower region of the hole 103 of the electrical wiring layer 115. It is preferable to form a) so that each electrical wiring layer is spaced apart from each other. This is to take a structure such that heat generated in the LED package 103 is not discharged through the electrical wiring layer 115, but is discharged through the heat dissipation wiring layer 118.

The present invention is formed by being bonded to both sides of the LED package 103 and the upper surface of the cover layer 111, spaced apart by leaving an air gap (air gap) between the flexible PCB 109 and the BLU chassis 101. It may further include a bent portion (125) for bending the flexible PCB to be formed.

The curved portion 125 may be formed using a known material having good flexibility and bending characteristics. The curved portion 125 may further improve the bending characteristics of the flexible PCB 109 to assist in generating more various backlight units.

That is, if the cross-sections of the BLU chassis 101 and the flexible PCB 109 have a 'L' shape, the flexible PCB 109 is formed by bending a 'L' shaped bending portion in particular. The air gap may be formed to be spaced apart from the sash 101.

As described above, according to the present invention, by forming the flexible PCB 109 in various forms, there is an advantage that a more flexible backlight unit can be manufactured.

3A to 3F are exemplary views showing step-by-step manufacturing procedures of a backlight unit having an LED according to an embodiment of the present invention.

Referring to FIG. 3A, a cross-sectional view of the flexible PCB 109 is shown.

The flexible PCB may be formed by sequentially depositing the electrical wiring layer 115, the insulating layer 112, and the cover layer 111 on the insulating film 116.

As described above, the insulating layer 116 is formed of any one of rosin-based flux, phenol, epoxy, polyimide, or teflon resin. It can form, and the thickness can be formed in the range of 10 micrometers-50 micrometers.

However, the insulating layer 116 should not be formed over the entire upper surface of the BLU chassis 101. For example, in the case of an 'L' shaped flexible PCB, an insulating film is formed on one side and an insulating film is not formed on the lower surface. That is, it can be said that the insulating film is formed to induce heat release to the lower surface by forming an insulating film on one side.

As described above, it is preferable that the insulating film is provided only in a predetermined region of the flexible PCB in order to induce heat emission to the lower surface or one side.

In addition, the electrical wiring layer 115 is formed of a metal material having good electrical conductivity such as copper (Cu) or aluminum (Al), and the insulating layer 112 and the cover layer 111 are formed using polyimide. Will be.

Referring to FIG. 3B, the predetermined region in which the LED package is mounted is formed.

That is, the cover layer 111 and the insulating layer 112 of the predetermined region of the flexible PCB is removed to form the electric wiring layer 115 is exposed.

Removal of the cover layer 111 and the insulating layer 112 may be performed by a dry etching method, a wet etching method, a mechanical cutting method by a drill or a photoresist method.

Referring to FIG. 3C, a hole 113 is formed by removing a predetermined region of the exposed electrical wiring layer.

The hole 113 is to make a space for the formation of the short-circuit insulating layer 117, it is possible to form a plurality of holes 113 in accordance with the needs of the invention.

Removal of a predetermined region of the electrical wiring layer may also be performed by a dry etching method, a wet etching method, a mechanical cutting method by a drill, or a photoresist method.

Referring to FIG. 3D, a short insulating layer 117 is formed by filling a material such as polyimide into the hole 113.

The short-circuit insulating layer 117 is made of any one material selected from rosin-based flux, phenol, epoxy, polyimide, or teflon resin. It may be formed.

Due to the formation of the short-circuit insulating layer 117, the electrical wiring layer of the lower region in which the LED package is to be mounted serves as the heat dissipation wiring layer 118.

Referring to FIG. 3E, the LED package is mounted on the exposed electrical wiring layer 115 and the heat dissipation wiring layer 118.

In the LED package, the LED chip 122 is mounted on the lead frame 119, and a phosphor and an encapsulant are formed thereon.

A lead frame SMD pad 120 is formed below the lead frame 119, and is bonded to the electrical wiring layer 115 and the heat dissipation wiring layer 118 by a soldering method using the SMD solder 121.

With this structure, most of the heat generated in the LED package is released to the heat dissipation wiring layer 118 by the holes 103 and the short-circuit insulating layer 117 formed on the bottom surface of the LED package, and ultimately the BLU chassis Outflow through the body to the outside.

Therefore, it is preferable that the area of the lead frame SMD pad 120 positioned at the center of the lower surface of the LED package is larger than the lead frame SMD pad 120 positioned at both ends.

Referring to FIG. 3F, a bent portion 125 is formed on both side surfaces of the LED package and an upper surface of the cover layer.

According to the present invention, the flexible PCB unit can be formed only by the flexible PCB itself, but it may further include a bent portion 125 to facilitate the bending.

The bent portion may be formed on both side surfaces of the LED package and the top surface of the cover layer 111, but may be formed on a predetermined region of the flexible PCB in which the LED package is not mounted according to the necessity of the invention.

The bent portion 125 can be formed using a known flexible material such as plastics. Due to the adoption of the bent portion 125, for example, the shape of the rear and side portions of the TV or computer may have more various shapes.

4A illustrates an example of a backlight unit having a plurality of LEDs according to an exemplary embodiment of the present invention.

Each LED serves as a point light source, and a plurality of LEDs gather to serve as surface light sources, and according to the needs of the invention, the number of LED packages may be adopted without limitation.

4B is a side view of a backlight unit having an LED according to an embodiment of the present invention.

Referring to FIG. 4B, a side view of the backlight unit in which the bent portion is omitted is shown for ease of description.

That is, referring to the side view, the short circuit insulating layer 117 is divided into an electric wiring layer 115 and a heat dissipation wiring layer 118. That is, since the heat dissipation wiring layer 118 for heat dissipation occupies most of the area of the backlight unit, rather than the area of the electric wiring layer 115 for circuit formation, the heat dissipation effect is maximized compared to the prior art.

5A is a plan view of a backlight unit having an LED including a bent portion according to an embodiment of the present invention.

The heat generated from the LED package is discharged through the heat dissipation wiring layer 118 located between the electric wiring layers 115, and the heat is not emitted upward as seen in FIG. 5A by the insulating film 116. That is, in the case of the 'L'-shaped flexible PCB, the heat is induced to the lower surface instead of the side, and heat is finally leaked out through the BLU chassis.

In addition, the bent portion 125 may be bonded to the cover layer 111 to form a backlight unit that is bent in various forms.

5B is an exemplary view of a backlight unit having an LED including a curved portion according to another embodiment of the present invention.

As described above, the bent part 125 may be formed along a line on which the LED package is mounted, but may be formed to be spaced apart from the line on which the LED package is mounted. The curved portion 125 may be formed regardless of the position because the curved portion 125 serves to assist the bending formation of the flexible PCB regardless of the LED package.

6 is a flow chart of a method of manufacturing a backlight unit having an LED according to an embodiment of the present invention.

First, a flexible PCB is formed on the BLU chassis (s601).

In the present invention, the BLU chassis is preferably formed of aluminum or an aluminum-based alloy, and the flexible PCB may be formed using a known flexible material having a free bending. For example, the electrical wiring layer included in the flexible PCB may be formed of copper (Cu), and the insulating layer and the cover layer may be formed using polyimide to form a flexible PCB having flexibility.

Subsequently, the cover layer and the insulating layer are removed on a predetermined region on the flexible PCB.

That is, a hole in which a kind of LED package is to be mounted is formed in a region where the LED package is bonded. The cover layer and the insulating layer may be removed by mechanical processing or etching.

After removing the cover layer and the insulating layer, the cover layer and the insulating layer are removed to form at least two holes in a predetermined area of the electrical wiring layer of the flexible PCB exposed (s603).

Preferably, the electrical wiring layer is formed of copper (Cu), and the hole may be formed by a photoresist method or a mechanical cutting process using a drill.

Thereafter, a step of forming a short insulating layer in the hole is performed (s604).

The short circuit insulating layer may be formed by injecting polyimide or the like into the hole, and the electrical wiring layer of the lower surface of the LED package is transformed into a heat dissipation wiring layer due to the formation of the short circuit insulating layer.

Lastly, at least two holes are formed between the short-circuit insulating layer and the LED package, thereby bonding the LED package using a lead frame SMD mounted pad (SMD) pad and SMD solder.

That is, in order to facilitate heat dissipation to the heat dissipation wiring layer formed between the short-circuit insulating layers, holes are formed, and areas of lead frame SMD (Surfice Mounted Device) pads and SMD solder which are in contact with the top surface of the heat dissipation wiring layer are formed. It is preferable to form widely.

As described above, according to the present invention, since heat generated in the LED package is directly transmitted to the BLU chassis through the heat dissipation wiring layer of the flexible PCB, the heat dissipation effect is excellent, and the backlight unit is not provided with the conventional thermal pad, metal PCB, and heat sink. Since it is possible to form the manufacturing process and manufacturing cost has the advantage of reducing.

The present invention has been described above in connection with specific embodiments of the present invention, but this is only an example and the present invention is not limited thereto. Those skilled in the art can change or modify the described embodiments without departing from the scope of the present invention, and within the equivalent scope of the technical spirit of the present invention and the claims to be described below. Various modifications and variations are possible.

101: BLU sash 102: heat sink
103: LED package 104: Thermal Pad
105: metal PCB 106: light guide plate
107: reflection sheet 108: diffusion sheet
109: flexible PCB 110: direction of heat movement
111: cover layer 112: insulating layer
113: hole 115: electrical wiring layer
116: insulating film 117: short circuit insulating layer
118: heat dissipation wiring layer 119: lead frame
120: leadframe SMD pad 121: SMD solder
122: LED chip 123: height of the LED package (H)
124: thickness of the cover layer and the insulating layer (h) 125: bend
131: bend of the flexible PCB

Claims (14)

Back Light Unit Chassis (BLU);
A flexible printed circuit board (PCB) formed on the BLU chassis; And
At least one LED package bonded onto the flexible PCB;
Backlight unit having an LED comprising a. The method of claim 1, wherein the flexible PCB,
Insulating film;
An electrical wiring layer formed on the insulating film;
An insulating layer formed on the electrical wiring layer; And
A cover layer formed on the insulating layer;
Backlight unit having an LED, characterized in that it comprises a. The method of claim 2, wherein the insulating layer and the cover layer,
Backlight unit having an LED, characterized in that formed using polyimide (polyimide). The method of claim 2, wherein the insulating film,
Rosin-based Flux, Phenolic, Epoxy, Polyimide, or Teflon resins formed using any one or more materials selected from LEDs Backlight unit provided. The backlight unit of claim 2, wherein the insulating layer has a thickness of about 10 μm to about 50 μm. The method of claim 1,
The thickness of the flexible PCB is a backlight unit having an LED, characterized in that 0.035 mm to 0.5 mm. The method of claim 1, wherein the junction of the flexible PCB and the LED package,
And removing a predetermined area of a cover layer and an insulating layer of the flexible PCB, and mounting the LED package on an electric wiring layer to which the predetermined area is removed and exposed. The method of claim 7, wherein the LED package and the electrical wiring layer,
A backlight unit with LEDs, characterized in that bonded using leadframe SMD (Surfice Mounted Device) pads and SMD solder. 9. The backlight unit of claim 8, wherein a height (H) from the SMD solder to an upper surface of the LED package is greater than a thickness (h) of the cover layer and the insulation layer. The method of claim 8,
The backlight unit having an LED, characterized in that formed to have at least two holes (hole) between the LED package and the electrical wiring layer. The LED of claim 10, wherein a short-circuit insulating layer for electrically shorting the electrical wiring layer is provided in a lower region of the hole among the electrical wiring layers, and the LEDs are formed to be spaced apart from each other. Backlight unit provided. The flexible PCB of claim 7, wherein the flexible PCB is formed to be bonded to both sides of the LED package and to an upper surface of the cover layer, and to be formed to be spaced apart from each other with an air gap at the BLU shot time. Backlight unit having an LED, characterized in that it further comprises a bent portion. Forming a flexible PCB on the BLU chassis;
Removing a cover layer and an insulating layer on a predetermined region on the flexible PCB; And
Mounting at least one LED package on the electrical wiring layer of the flexible PCB to which the cover layer and the insulating layer are removed and exposed;
Method of manufacturing a backlight unit having an LED comprising a. The method of claim 13, wherein the mounting step of the LED package,
Forming at least two holes in a predetermined region of the electrical wiring layer of the flexible PCB to which the cover layer and the insulating layer are removed and exposed;
Forming a short insulating layer in the hole; And
Bonding an LED package using a leadframe SMD mounted pad (SMD) pad and SMD solder such that at least two holes are formed between the short insulation layer and the LED package;
Method of manufacturing a backlight unit having an LED, characterized in that.

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