Abstract:
The invention relates to a side-emitting LED package and a manufacturing method of the same. The invention provides a side-emitting LED package for emitting light from a light source sideward including a substrate with an electrode formed thereon. The package also includes a light source disposed on the substrate, a molded part that covers and protects the substrate with the light source thereon, and a reflective layer that covers an outer surface of the molded part. The molded part with the reflective layer forms a light transmitting surface in one side thereof. The invention allows easy manufacture of a reflecting surface in a desired shape, miniaturization regardless of the LED chip size, mass-production in an LED array, significantly improving productivity.

Description:
CLAIM OF PRIORITY 
       [0001]    This application claims the benefit of Korean Patent Application No. 2005-46796 filed on Jun. 1, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a side-emitting LED package for emitting light from one side thereof, and a manufacturing method of the same. More particularly, the invention relates to a side-emitting LED package which has a reflecting surface easily manufactured in a desired form, can be mass-produced in a compact size regardless of an LED chip size, and can easily be adapted to have an LED array inside thereof, thereby significantly improving productivity, and a manufacturing method of the same. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, a backlight such as used in a mobile phone or a PDA adopts an LED package having a light transmitting surface in one side thereof for its light source. 
         [0006]    Such LED packages are becoming slimmer as the mobile phones are becoming slimmer nowadays. 
         [0007]    Aside-emitting LED package  200  illustrated in  FIG. 1(   a ) is a structure, in which a molded body  210  covers a lead frame having an LED chip therein, and thus its thickness is limited to be about 0.5 T. Therefore, such a method is limited in reducing the thickness. 
         [0008]      FIG. 1(   b ) illustrates another structure of LED package  230 . In this conventional technology, an LED chip  234  is mounted on a substrate  232 , which is covered by a molded body  236  having a cavity therein bonded to the substrate  232 . Then, a solution of phosphor and epoxy mixed together is injected and cured in the cavity, and diced afterwards. This conventional method, however, entails a complicated process, and thus is not efficient in terms of productivity. 
         [0009]      FIG. 2(   a ) illustrates another conventional side-emitting LED package  250 . This conventional structure is taught in Japanese Patent Application Publication 1997-83019, in which an LED is used for a light source  252 , and light from the LED is induced toward one side of the package to be emitted out of the package. 
         [0010]    In this conventional structure, an outer surface of the light source  252  is wrapped with a lens, and a retainer  256  wraps around the lens  254 . The retainer  256  has an opening in one side to form a light transmitting surface  256   a , and a reflecting surface  258  is formed on the opposite side of the light transmitting surface  258  inside the retainer  256 . 
         [0011]    This conventional structure also, however, entails a complicated and cumbersome manufacturing process, in which the retainer  256  and the reflecting surface  258  should be prepared separately to wrap around the lens  254 . 
         [0012]    In addition,  FIG. 2(   b ) illustrates another LED package  270 , which is disclosed in U.S. Pat. No. 6,674,096 granted to Sommers, Mathew L. In this structure, a molded part  274  wraps around an LED chip  272 , and has a centrally depressed reflecting surface  276  on an upper surface thereof. The reflecting surface  276  has a reflective layer  278  formed thereon to form a light transmitting surface around the sides of the molded part  274 . However, this conventional technology also bears a problem in that the light transmitting surface  280  is not formed in one particular direction, and thus the reflected light is not focused but tends to be scattered. 
       SUMMARY OF THE INVENTION 
       [0013]    The present invention has been made to solve the foregoing problems of the prior art and it is therefore an object of the present invention to provide a side-emitting LED package which does not additionally require an injection-molded material and thus can have minimal thickness, and a manufacturing method of the same. 
         [0014]    It is another object to provide a PCB type side-emitting LED package having a reflecting surface that can easily be manufactured in a desired shape, which can be mass-produced, and a manufacturing method of the same. 
         [0015]    It is further another object to provide a side-emitting LED package which can be mass-produced and is not affected by an LED chip size, and can have an LED array inside thereof, and a manufacturing method of the same. 
         [0016]    It is yet another object to provide a side-emitting LED package which adopts Epoxy Molding Compound (EMC) transfer molding to minimize color dispersion, and a manufacturing method of the same. 
         [0017]    According to an aspect of the invention for realizing the object, there is provided a side-emitting LED package for emitting light from a light source sideward, including: a substrate with an electrode formed thereon; a light source electrically connected to the electrode and disposed on the substrate; a molded part covering and protecting the substrate and the light source disposed on the substrate; a reflective layer covering an outer surface of the molded part; and a light transmitting surface formed in one side of the package with respect to a plane where the light source is disposed. 
         [0018]    According to another aspect of the invention for realizing the object, there is provided a A manufacturing method of an LED package for emitting light from a light source sideward, the method comprising steps of: (i) providing a substrate with electrodes formed thereon; (ii) disposing light sources on the substrate; (iii) forming a molded part on the substrate and the light sources disposed on the substrate; (iv) dicing the molded part to divide into individual packaging parts; (v) forming a reflective layer covering an outer surface of the molded part; and (vi) dicing one side of the molded part and the reflective layer to form a light transmitting surface in one side. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0020]      FIG. 1  illustrates side-emitting LED packages according to the prior art, in which, (a) is a structure including a molded body, and (b) is a structure including a printed circuit board and a molded body; 
           [0021]      FIG. 2  illustrates other side-emitting LED packages according to the prior art, in which, (a) is a structure including a lens, a reflecting surface and a retainer, and (b) is a structure including a reflecting surface and a reflective layer that are centrally depressed; 
           [0022]      FIG. 3  is a perspective view illustrating a side-emitting LED package according to the present invention; 
           [0023]      FIG. 4  is a sectional view illustrating embodiments of the side-emitting LED package according to the present invention, in which (a) illustrates a reflective layer in a curved surface, (b) illustrates a reflective layer in a horizontal planar top surface with a sloped planar side surface, and (c) illustrates a reflective layer in a sloped planar surface; 
           [0024]      FIG. 5  is a sectional view illustrating the side-emitting LED package according to the present invention, in which (a) is a structure having one LED chip as a light source, and (b) is a structure having a plurality of LED chips as a light source; 
           [0025]      FIG. 6   a  illustrates a manufacturing method of the side-emitting LED package having one LED chip as a light source; 
           [0026]      FIG. 6   b  is a detailed view of the manufacturing method of the side emitting LED package shown in  FIG. 6   a , with magnified dicing lines; 
           [0027]      FIG. 7   a  illustrates a manufacturing method of the side-emitting LED package having a plurality of LED chips as a light source; and 
           [0028]      FIG. 7   b  is a detailed view of the manufacturing method shown in  FIG. 7   a  with magnified dicing lines. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0029]    Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 
         [0030]    Referring to  FIGS. 3 to 5 , a side-emitting LED package  1  according to the present invention is designed to emit light from an LED chip or a light source  5  to one side. The direction of light emission preferably forms a right angle with a plane where the LED chip is mounted. 
         [0031]    The side-emitting LED package  1  according to the present invention has a substrate  15  with electrodes  15   a  formed thereon. The substrate  15  is preferably a printed circuit board (PCB) or a ceramic substrate having patterned electrodes (not shown) or the electrodes  15   a  formed as vertical electrodes such as vias. 
         [0032]    In addition, the LED chip as the light source  5  is disposed on the substrate  15  and electrically connected to the electrodes  15   a . Either a horizontal type of LED chip having electric terminals formed only on an upper surface thereof or a vertical type of LED chip having electric terminals formed on upper and lower surfaces thereof is applicable in the present invention. 
         [0033]    In addition, a molded part  10  is formed to cover the substrate  15  with the light source  5  disposed thereon. The molded part  10  is formed by curing resin, etc., and preferably made of transparent Epoxy Molding Compound (EMC) containing phosphor to minimize color dispersion. 
         [0034]    Various forms of mold (not shown) can be used in the process of forming the molded part  10 . For example, as shown in  FIG. 4(   a ), the molded part  10  can have a curved surface, or as shown in  FIG. 4(   b ), can have a horizontal planar top surface with a sloped planar side surface opposed to a light transmitting surface  17 , or as shown in  FIG. 4(   c ), can have a sloped planar surface. The desired shape of the molded part  10  as described can be obtained by machining the mold in advance according to the desired structure of the molded part  10 . 
         [0035]    When the molded part  10  is formed as just described, it is machined according to the desired shape for each package. 
         [0036]    When the molded part  10  is completed in a desired form as described above, a reflective layer  20  is formed thereon with the light transmitting surface  17  formed on one particular surface thereof. 
         [0037]    The reflective layer  20  can be formed by depositing metal selected from a group consisting of Al, Au, Ag, Ni, W, Ti and Pt or attaching a thin film directly on an outer surface of the molded part  10 . Alternatively, if an electrode (not shown) for plating is formed on the substrate  15 , the reflective layer  20  can be formed by plating. The reflective layer  20  completely wraps the molded part  10  to prevent light from leaking so that light is emitted only through the light transmitting surface  17  formed on one side of the molded part  10 . 
         [0038]    Therefore, in the same fashion as the molded part  10 , the reflective layer  20  may be a curved surface, a horizontal planar top surface with a sloped planar side surface opposed to the light transmitting surface  17 , and a sloped planar surface. 
         [0039]    The light transmitting surface  17  preferably forms a right angle with the LED chip forming the light source  5  or with a planar surface of the substrate  15  where the LED chip is mounted. In addition, the light transmitting surface  17  is preferably composed of a single planar surface so that light is emitted with a specific directivity through one particular side. 
         [0040]    Alternatively, the light transmitting surface  17  can be composed of a plurality of planar surfaces or a curved surface having a predetermined curvature. 
         [0041]    As shown in  FIG. 5(   a ), in the side-emitting LED package  1  according to the present invention, at least one LED chip is disposed inside the molded part  10  to form the light source  5 . That is, as shown in  FIG. 5(   b ), the light source  5  may be composed of one LED chip or a plurality of LED chips in accordance with optical requirements. 
         [0042]    In case of a plurality of LED chips forming a single light source  5 , solder resistors  22  are formed between the LED chips on the substrate  15  to electrically insulate the reflective layer from the electrodes  15   a.    
         [0043]    A manufacturing method of a side-emitting LED package according to the present invention will be explained in detail hereunder. 
         [0044]    As shown in  FIG. 6 , the manufacturing method  100  of the side-emitting LED package according to the present invention starts with a step  102  of providing a substrate  15  with electrodes  15   a  formed thereon. On the substrate  15 , solder resistors  22 , which will be explained later, are formed between LED chips. 
         [0045]    In this step  102 , the substrate  15  may be a printed circuit board (PCB) or a ceramic substrate having the electrodes  15   a  as vertical electrodes  15   a  such as vias or patterned electrodes (not shown). The electrodes  15   a  such as vias are formed in each area where the LED chip is disposed to form a light source  5 . When needed, an additional patterned electrode can be formed to connect the vias with the light source  5 . 
         [0046]    The next step  104  is disposing a plurality of light sources on the substrate  15 . 
         [0047]    In this step  104 , a plurality of LED chips are simultaneously mounted on a single substrate  15  to form the light sources  5  and electrically connected to the electrodes  15   a  of the substrate  15 . 
         [0048]    In the next step  106 , a molded part  10  is formed on the substrate  15  with the light sources  5 . 
         [0049]    In this step  106 , the molded part  10  containing phosphor is formed by transfer molding of Epoxy Molding Compound (EMC) to minimize color dispersion once it is cured. 
         [0050]    In addition, various forms of mold can be used to form the molded part  10 , such as a curved surface, a horizontal planar top surface with a sloped side surface opposed to the light transmitting surface  17  and a sloped planar surface, as explained with reference to  FIG. 4 . 
         [0051]    After the molded part  10  is formed as described, it is diced in the next step  108 . 
         [0052]    In this step  108 , only the molded part  10  is diced or etched to form a desired shape of molded part  10  for packaging each LED chip that forms each light source  5 . In this step  108 , the molded part  10  is diced or etched such that its peripheral end portions partially cover the solder resistors  22  on the substrate  15 . 
         [0053]    In the next step  110 , a reflective layer  20  is formed to cover an outer surface of the molded part  10 . The reflective layer  20  can be formed by depositing metal having high reflectivity selected from a group consisting of, for example, Al, Au, Ag, Ni, W, Ti and Pt on the molded part  10 , or attaching a high reflectivity film on the molded part  10 . Here, it is preferable that the reflective layer  20  completely covers an outer surface of the molded part  10  to prevent leaking of light to the outside. 
         [0054]    In addition, the manufacturing method of the present invention includes the last step  112 , in which a side of the molded part  10  and the reflective layer  20  is diced to form a light transmitting surface  17 . 
         [0055]    In this step  112  of forming the light transmitting surface  17 , a side of the molded part  10  and the reflective layer  20  is diced simultaneously so that the entire outer surface of the molded part  10  except the portion of the light transmitting surface  17  is covered by the reflective layer  20 . 
         [0056]    Here, the peripheral end portions of the reflective layer  20  partially cover the solder resistors  22  on the substrate  15  to ensure electrical insulation between the reflective layer  20  and the electrodes  15   a.    
         [0057]    In addition, the above step  112  includes cutting the substrate  15  along horizontal and vertical cutting lines  30  into individual LED packages. 
         [0058]      FIG. 7  illustrates step-by-step a manufacturing method  150  of a side-emitting LED package having a light source  5  comprising a plurality of LED chips disposed inside a single molded part  10  with a reflective layer  20  thereon. 
         [0059]    The manufacturing method  150  of a side-emitting LED package according to the present invention starts with providing a substrate  15  with electrodes  15   a  formed thereon, as explained with reference to  FIG. 6 . 
         [0060]    In each area where an LED chip will be disposed later on the substrate  15  to form a light source  5 , solder resistors  22  are formed to electrically insulate the electrodes  15   a  in this area from other parts. A plurality of vias are formed to provide the electrodes  15   a.    
         [0061]    In the next step  154 , the LED chips are disposed on the substrate  15  to form a light source  5 , and wires are installed to connect the LED chips to the electrodes  15   a.    
         [0062]    In the next step  156 , a molded part  10  is formed covering the substrate and the light source  5  disposed on the substrate. The molded part  10  is made of transparent Epoxy Molding Compound (EMC). 
         [0063]    Once the molded part  10  is completed as described, it is diced in the next step  158 . 
         [0064]    In this step  158 , the molded part  10  is diced into a plurality of packaging parts such that a desired number of LED chips form a single light source  5  inside a single molded part  10  or a single packaging part. In this step  158 , peripheral end portions of the molded part  10  partially cover the solder resistors  22  on the substrate  15 . 
         [0065]    The solder resistors  22  block electrical connection between the electrodes  15   a  and the reflective layer  20 , which will be formed later. 
         [0066]    In the next step  160 , as explained with reference to  FIG. 6 , metal having high reflectivity, for example, Al, Au, Ag, Ni, W, Ti and Pt, is deposited or plated on an outer surface of the molded part  10 , or a high reflectivity film is attached on the molded part  10 . Lastly, in the step  162 , a side of the molded part  10  and the reflective layer  20  is diced to form a light transmitting surface  17  on one side of thereof. 
         [0067]    When the reflective layer  20  is formed as described above, the substrate  15  is cut horizontally and vertically to obtain individual side-emitting LED packages  1 , each having a plurality of LED chips therein to form a light source  5 . 
         [0068]    According to the present invention as set forth above, no other molded material is needed in addition to the molded part  10  so that the package has a minimal thickness to be easily applied to various miniaturized electronic devices. 
         [0069]    In the present invention, the mold (not shown) is manufactured freely in various forms to obtain various forms of the molded part  10 , thereby obtaining a desired form of the reflective layer  20  on the molded part  10 . 
         [0070]    In addition, the present invention is not restricted by a molded material other than the molded part, resulting in a compact, thin structure. Also, as the light transmitting surface is formed in a side perpendicular with respect to a plane where the LED chip is mounted on, the package can be manufactured in a small thickness regardless of the LED chip size. 
         [0071]    In addition, the substrate is processed as a PCB, that is, the processes of mounting, molding and dicing are conducted as a PCB manufacturing process, enabling mass-production in an array type. 
         [0072]    Furthermore, the invention adopts the molded part made of transparent Epoxy Molding Compound (EMC) containing phosphor to minimize color dispersion after it is cured, thereby significantly improving optical properties of the package. 
         [0073]    The present invention has been described with reference to preferred embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. While the present invention has been shown and described in connection with the preferred embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.