Abstract:
Provided are a light emitting device package and a lighting system comprising the same. The light emitting device package comprises a package body having a trench, a metal layer within the trench, and a light emitting device over the metal layer.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    The present application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2009-0013575 (filed on Feb. 18, 2009), which is hereby incorporated by reference in its entirety. 
       BACKGROUND 
       [0002]    Embodiments relate to a light emitting device package and a lighting system including the same. 
         [0003]    A light emitting diode (LED) may constitute a light emitting source using compound semiconductor materials such as GaAs-based materials, AlGaAs-based materials, GaN-based materials, InGaN-based materials and InGaAlP-based materials. 
         [0004]    Light emitting devices are being variously applied in the fields of optical devices and high-power electronic devices. 
         [0005]    Such a light emitting device is packaged, and thus is being used as a light emitting apparatus that emits light having various colors. The light emitting apparatus is being used as a light source in various fields, e.g., lighting displays, character displays, and image displays. 
       SUMMARY 
       [0006]    Embodiments provide a light emitting device package and a lighting system including the same that enhance thermal emission efficiency. 
         [0007]    In one embodiment, a light emitting device package comprises: a package body having a trench; a metal layer within the trench; and a light emitting device over the metal layer. 
         [0008]    In another embodiment, a lighting system comprises: a light emitting module comprising a light emitting device package including a package body having a trench; a metal layer within the trench; and a light emitting device over the metal layer. 
         [0009]    The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features will be apparent from the description and drawings, and from the claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a sectional view of a light emitting device package according to an embodiment. 
           [0011]      FIGS. 2 to 5  are views illustrating a process of manufacturing a light emitting device package according to an embodiment. 
           [0012]      FIG. 6  is a sectional view of a light emitting device package according to another embodiment. 
           [0013]      FIG. 7  is a perspective view of a lighting unit according to an embodiment. 
           [0014]      FIG. 8  is a perspective view of a backlight unit according to an embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0015]    Hereinafter, a light emitting device package according to an embodiment and a lighting system including the same will be described with reference to accompanying drawings. 
         [0016]    In the following description, it will be understood that when a layer (or film) is referred to as being ‘on’ another layer or substrate, it can be directly on another layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being ‘under’ another layer, it can be directly under another layer, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being ‘between’ two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. 
         [0017]      FIG. 1  is a sectional view of a light emitting device package according to an embodiment. 
         [0018]    A light emitting device package according to an embodiment may include a package body  110  having a trench, a metal layer  120  disposed in the trench, an adhesion layer  150  disposed on the metal layer  120 , and a light emitting device  160  disposed on the adhesion layer  150 . 
         [0019]    In an embodiment, the light emitting device may be a light emitting diode (LED), but is not limited thereto. 
         [0020]    Although a horizontal-type light emitting device chip is illustrated in  FIG. 1 , the present disclosure is not limited thereto. For example, the embodiments may be applicable to a vertical-type light emitting device chip. 
         [0021]    In an embodiment, the light emitting device package may have a structure in which an anisotropic wet or dry etching process is performed on the package body  110  to define a via hole, and then an electroplating process is performed to fill the via hole. 
         [0022]    At this time, current may be supplied through the via hole defined at edges of a bottom surface of the light emitting device to emit heat through the via hole defined below the light emitting device chip, thereby improving thermal emission efficiency. 
         [0023]    In the light emitting device according to an embodiment, the percentage of a metal having high heat conductivity may increase, and a narrow and deep thermal diffusion layer may be disposed in a bottom surface of the light emitting device package to improve the thermal emission efficiency. 
         [0024]    Also, since an anisotropic wet etching process considering a crystal orientation of a substrate is performed to define a narrow and deep trench at a low cost, a narrow and deep thermal diffusion layer may be formed when a metal having high heat conductivity is filled using an electroplating technology. 
         [0025]    Hereinafter, a method of packaging a light emitting device will be described with reference to  FIGS. 2 to 5 . 
         [0026]    As shown in  FIG. 2 , a cavity C for mounting a light emitting device  160  may be formed in a package body  110 , but is not limited thereto. 
         [0027]    The package body  110  may be a silicon (Si) substrate, but is not limited thereto. The package body  110  may have a &lt;110&gt; orientation. 
         [0028]    In a related art, a &lt;100&gt; Si wafer used for forming a thermal emission via has a &lt;111&gt; crystal plane and an inclined angle of about 54.7°. Thus, when a wet etching process is performed, the thermal emission via has a shape whose width gradually narrows or expands toward a downward direction. Thereafter, there is a limitation that it is difficult to form a narrow and deep trench. 
         [0029]    Also, an anisotropic dry etching process such as a reactive ion etching (RIE) process except the wet etching process may be performed to form a plurality of narrow and deep trenches. However, considering an expensive manufacturing cost and processing time, it is difficult to apply the anisotropic dry etching process to a process of manufacturing an LED package. 
         [0030]    Thus, in an embodiment, a &lt;110&gt; Si wafer in which a &lt;111&gt; crystal plane is perpendicular thereto may be used to form a narrow and deep trench using the anisotropic wet etching process that is an inexpensive etching process. 
         [0031]    Thereafter, as shown in  FIG. 2 , a plurality of first trenches T 1  may be formed in the package body  110  having the cavity C. Each of the first trenches T 1  may have a vertical width greater than a horizontal width thereof with respect to a vertical section of the respective first trenches T 1 . 
         [0032]    The plurality of first trenches T 1  may be configured to form a metal layer  120  for emitting heat. At this time, a cathode lead trench Tc and an anode lead trench Ta may be formed together with the plurality of first trenches T 1 . 
         [0033]      FIG. 3  is a plan view of a case in which an anisotropic wet etching process is performed on a &lt;110&gt; Si wafer. 
         [0034]    A solution in which KOH may be mixed with water and isopropyl alcohol may be used as an anisotropic etching solution used for forming the trenches, but is not limited thereto. For example, the etching process may be performed using about 23% by wt. of KOH, about 13% by wt. of isopropyl alcohol, and about 63% by wt. of water, but is not limited thereto. 
         [0035]    According to an embodiment, an etch mask (not shown) disposed in a direction parallel to that of a (111) plane is patterned on a package body  110 , e.g., a bottom surface of a &lt;110&gt; Si substrate package to form a narrow and deep first trench T 1  defined in a vertical direction using a wet etching process. 
         [0036]    According to an embodiment, a plurality of narrow and deep first trenches T 1  defined in a vertical direction may be formed using an anisotropic etching process in consideration of an etching property according to a crystal orientation of a package body  110 . 
         [0037]    In the light emitting device package according to an embodiment and the method of manufacturing the same, the percentage of the metal having high heat conductivity may increase, and the narrow and deep thermal diffusion layer may be disposed in the bottom surface of the light emitting device package to improve the thermal emission efficiency. 
         [0038]    As shown in  FIG. 4 , a plurality of metal layers  120  is formed in the plurality of first trenches T 1 . For example, the metal layers  120  may be deposited within the plurality of first trenches T 1  using an electroplating technology to fill the trenches. 
         [0039]    Each of the metal layers  120  may have a rectangular bar-shape in a vertical section. At this time, a cathode lead trench Tc and an anode lead trench Ta together with the metal layers  120  may be filled to form a cathode lead  130  and an anode lead  140 . 
         [0040]    Since an anisotropic wet etching process considering a crystal orientation of a substrate is performed to define a narrow and deep trench at a low cost, a narrow and deep thermal diffusion layer may be formed when a metal having high heat conductivity is filled using an electroplating technology. 
         [0041]    A reflection layer  180  may be formed on the package body  110 , but is not limited thereto. The reflection layer  180  may be a conductive reflection layer  180 . For example, the reflection layer  180  may include a metal layer containing Al, Ag, or an alloy containing Al or Ag. The reflection layer  180  may be configured to electrically separate the cathode lead  130  from the anode lead  140 . 
         [0042]    Thereafter, an adhesion layer  150  may be formed on the reflection layer  180 . 
         [0043]    For example, the light emitting device  160  may be attached to the package body  110  using a polymer adhesive or a plated eutectic metal. 
         [0044]    Also, the light emitting device  160  may be attached to the package body  110  through a soldering process using Ag conductive epoxy having improved process or a eutectic bonding process in case where highly thermal conductivity is required, but is not limited thereto. 
         [0045]    As shown in  FIG. 5 , a wire bonding process is performed on the light emitting device  170 . 
         [0046]    For example, the cathode lead  130  may be connected to a cathode electrode (not shown) of the light emitting device  160 , and the anode lead  140  may be connected to an anode electrode of the light emitting device  160 . 
         [0047]    For example, the wire  170  may include one or more wires of a gold wire, a copper wire, and an aluminium wire. The wire bonding process may include ball wire bonding or edge wire bonding. 
         [0048]    In  FIG. 5 , when the light emitting device  160  is a vertical-type light emitting device  160 , the light emitting device is electrically connected to the metal layer. However, the light emitting device  160  may not be electrically connected to the metal layer  120 . 
         [0049]    When the light emitting device  160  is the vertical-type light emitting device  160 , the adhesion layer  150  may have conductivity, and only one wire may be used. 
         [0050]    Also, when the light emitting device  160  is the vertical-type light emitting device  160 , the metal layer  120  may serve as an electrode layer. Also, the metal layer  120  may be electrically connected to the light emitting device  160 . In this case, a separate cathode lead and anode lead may not be formed. 
         [0051]    When the light emitting device  160  is bonded using a flip chip bonding technique, the wire is not required. Also, electrodes of the light emitting device  160  may be electrically connected to the cathode lead  130  and the anode lead  140 . 
         [0052]      FIG. 6  is a sectional view of a light emitting device package according to another embodiment. 
         [0053]    A light emitting device package of  FIG. 6  according to another embodiment may adopt technical properties of the light emitting device according to an embodiment. 
         [0054]    The light emitting device package according to another embodiment may include barriers  180  disposed on a package body  110  of both sides of a light emitting device  160  and a sealant  190  disposed on the light emitting device  160 . 
         [0055]    In an embodiment, at least one barrier  180  may be formed when the sealant  190  is formed. The barrier  180  may help the formation of the sealant  190  as well as prevent a lifting phenomenon of the sealant  190 . The barrier  180  may include an oxide layer or a nitride layer, but is not limited thereto. 
         [0056]    The sealant  190  may include a phosphor (not shown). For example, a sealing method of the sealant  190  may include a dispensing method, a casting molding method, a transfer molding method, and a vacuum printing method. 
         [0057]    Also, a blue light emitting device may use a yellow phosphor such as yttrium aluminum garnet (YAG) and terbium aluminum garnet (TAG) as a phosphor, or an UV light emitting device may use a (red/green/blue) three-colored phosphor as a phosphor, but is not limited thereto. 
         [0058]    In the light emitting device package of  FIG. 6  according to another embodiment, the sealant  190  may have a dome shape by the barriers  180  including a dielectric, but is not limited thereto. 
         [0059]    According to the light emitting device package according to the embodiments and the method of manufacturing the same, in a wafer level packaging, the percentage of the metal having the high heat conductivity may increase, and the narrow and deep thermal diffusion layer may be disposed in the bottom surface of the light emitting device package to improve the thermal emission efficiency. 
         [0060]    Also, since the anisotropic wet etching process considering the crystal orientation of the substrate is performed to define the narrow and deep trench at a low cost, the narrow and deep thermal diffusion layer may be formed when the metal having the high heat conductivity is filled using the electroplating technology. 
         [0061]    The light emitting device package according to an embodiment may be applicable to a lighting system. The lighting system may include a lighting unit illustrated in  FIG. 7 , a backlight unit illustrated in  FIG. 8 , traffic lights, a vehicle headlight, and a sign. 
         [0062]      FIG. 7  is a perspective view of a lighting unit according to an embodiment. 
         [0063]    Referring to  FIG. 7 , a lighting unit  1100  may include a case body  1110 , a light emitting module  1130  disposed in the case body  1110 , and a connection terminal  1120  disposed in the case body  1110  to receive a power from an external power source. 
         [0064]    The case body  1110  may be formed of a material having an improved heat dissipation characteristic. For example, the case body  1110  may be formed of a metal material or resin material. 
         [0065]    The light emitting module  1130  may include a substrate  1132  and at least one light emitting device package  1210  mounted on the substrate  1132 . 
         [0066]    A circuit pattern may be printed on an insulation material to form the substrate  1132 . For example, the substrate  1132  may include a printed circuit board (PCB), a metal core PCB, a flexible PCB, or a ceramic PCB. 
         [0067]    Also, the substrate  1132  may be formed of a material that can effectively reflect light. A surface of the substrate  1132  may be coated with a colored material, e.g., a white or silver-colored material by which light is effectively reflected. 
         [0068]    At least one light emitting device package  1210  may be mounted on the substrate  1132 . The light emitting device package  1210  may include at least one light emitting diode (LED)  100 . The LED  100  may include a colored LED that emits red, green, blue, or white light and an UV LED that emits ultraviolet (UV) light. 
         [0069]    The light emitting module  1130  may include a plurality of light emitting device packages  1210  to obtain various colors and brightness. For example, a white LED, a red LED, and a green LED may be disposed in combination with each other to secure a high color rendering index (CRI). 
         [0070]    The connection terminal  1120  may be electrically connected to the light emitting module  1130  to supply a power. As shown in  FIG. 7 , although the connection terminal  1120  is screw-inserted into an external power source in a socket manner, the present disclosure is not limited thereto. For example, the connection terminal  1120  may have a pin shape. Thus, the connection terminal  1120  may be inserted into the external power source or connected to the external power using an interconnection. 
         [0071]      FIG. 8  is a perspective view of a backlight unit according to an embodiment. 
         [0072]    A backlight unit  1200  according to an embodiment may include a light guide plate  1210 , a light emitting module  1240 , a reflective member  1220 , and a bottom cover  1230 , but is not limited thereto. The light emitting module  1240  may contact at least one surface of the light guide plate  1210  to provide light the light guide plate  1210 , but is not limited thereto. The reflective member  1220  may be disposed below the light guide plate  1210 . The bottom cover  1230  may receive the light guide plate  1210 , the light emitting module  1240 , and the reflective member  1220 . 
         [0073]    The light guide plate  1210  may diffuse light to produce planar light. The light guide plate  1210  may be formed of a transparent material. For example, the light guide plate  1210  may be formed of one of an acrylic resin-based material such as polymethylmethacrylate (PMMA), a polyethylene terephthalate (PET) resin, a poly carbonate (PC) resin, a cyclic olefin copolymer (COC) resin, and a polyethylene naphthalate (PEN) resin. 
         [0074]    The light emitting module  1240  may provide light to at least one surface of the light guide plate  1210 . Thus, the light emitting module  1240  may be used as a light source of a display device including the backlight unit. 
         [0075]    The light emitting module  1240  may contact the light guide plate  1210  but is not limited thereto. 
         [0076]    In particular, the light emitting module  1240  may include a substrate  1242  and a plurality of light emitting device package  200  mounted on the substrate  1242 . The substrate  1242  may contact the light guide plate  1210 , but is not limited thereto. 
         [0077]    The substrate  1242  may be a PCB including a circuit pattern (not shown). However, the substrate  1242  may include a metal core PCB or a flexible PCB as well as the PCB, but is not limited thereto. 
         [0078]    The plurality light emitting device packages  200  may be mounted on the substrate  1242 . Also, a light emitting surface of each of the light emitting device packages  200  may be spaced a predetermined distance from the light guide plate  1210 . 
         [0079]    The reflective member  1220  may be disposed below the light guide plate  1210 . The reflective member  1220  reflects light incident onto a bottom surface of the light guide plate  1210  to proceed in an upward direction, thereby improving brightness of the backlight unit. For example, the reflective member  1220  may be formed of one of PET, PC, and PVC, but is not limited thereto. 
         [0080]    The bottom cover  1230  may store the light guide plate  1210 , the light emitting module  1240 , and the reflective member  1220 . For this, the bottom cover  1230  may have a box shape with an opened upper side, but is not limited thereto. 
         [0081]    The bottom cover  1230  may be formed of a metal material or a resin material. Also, the bottom cover  1230  may be manufactured using a press forming process or an extrusion molding process. 
         [0082]    Any reference in this specification to “one embodiment,” “an embodiment,” “example embodiment,” etc., means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with any embodiment, it is submitted that it is within the purview of one skilled in the art to effect such feature, structure, or characteristic in connection with other ones of the embodiments. 
         [0083]    Although embodiments have been described with reference to a number of illustrative embodiments thereof, it should be understood that numerous other modifications and embodiments can be devised by those skilled in the art that will fall within the spirit and scope of the principles of this disclosure. More particularly, various variations and modifications are possible in the component parts and/or arrangements of the subject combination arrangement within the scope of the disclosure, the drawings and the appended claims. In addition to variations and modifications in the component parts and/or arrangements, alternative uses will also be apparent to those skilled in the art.