Abstract:
The present invention provides erected LED package structure, which includes: a carrier substrate having a first surface, a second surface and a plurality of through holes passed through the first surface and the second surface of the carrier substrate, and the conductive material filled with each of the through holes; a LED having a semiconductor layer capable of the light emitting and an N electrode and a P electrode formed on the two sides of the semiconductor layer thereon; a first transparent carrier substrate having a metal layer thereon, in which the metal layer electrically connected to the N electrode of the LED and to the conductive material which is formed on the first surface of the carrier substrate; a second transparent carrier substrate having another metal layer thereon, in which another metal layer electrically connected to the P electrode of the LED and to another conductive material which is formed on the first surface of the carrier substrate; and a plurality of connecting elements electrically connected to the plurality of conductive material which is formed on the second surface of the carrier substrate.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention is a light emitting diode (LED) package structure and more particularly is a package structure that the LED is vertically disposed to form a LED with longitudinal package structure. 
         [0003]    2. Description of the Prior Art 
         [0004]    Light emitting diode (LED) is a light emitting element is an illuminate element used to directly transform the electrical power to light power without transforming the electrical power to heat power. Therefore, LED is also called the luminescence emitting element. LED not only includes high illuminant efficiency but also is a micro solid state illuminator made in a semiconductor chip form. The voltage is inputted in two sides of the p-n junction and the current is able to flow through to generate electrons and holes flowing toward the p-n junction, and the electrons and holes are connected with the p-n junction to release photons. 
         [0005]    Generally, the illumination of the LED in the present art is equal to or half of the efficiency of the illumination of the cold cathode fluorescent lamp (CCFL). The illuminant efficiency of the LED is related to the illuminant efficiency of the semiconductor chip itself and the extraction efficiency of the semiconductor chip package structure. The development of the illuminant efficiency is to develop the electroluminescent material and to increase the crystallizability of the semiconductor chip to enhance the quantum efficiency inside the semiconductor chip. 
         [0006]    By the extraction efficiency of the LED package structure, the light generated by the semiconductor chip is reflected to the interior of the semiconductor chip by the interface total reflection. Because the light was reflected to the interior of the semiconductor by the interface total reflection, the reflective light was absorbed by the illuminant layer, electrode and substrate. Therefore, the extraction efficiency from the exterior to the semiconductor is less than the photon efficiency in the interior of the semiconductor. 
         [0007]    According to the description above, the LED is a light source with lower power consumption than the conventional incandescent lamp or fluorescent lamp and the size of LED is smaller and lighter than the conventional lamps. But how to enhance the extraction efficiency of the LED package structure to get higher overall efficiency in the quantum efficiency inside the semiconductor chip of the LED is the important issue in current technology. 
       SUMMARY OF THE INVENTION 
       [0008]    According to the problems described above, the main object of the present invention is to provide a light emitting diode (LED) with longitudinal package structure used to decrease the covered portion of the LED and enhance the illuminative efficiency. 
         [0009]    Another object of the present invention is to produce the transparent carrier substrate and LED at the same time and reduce the package time of the LED. 
         [0010]    Another object of the present invention is to saw the LED package structure by customers&#39; request after the LED is electrically connected to the carrier substrate without increasing the package time. 
         [0011]    The other object of the present invention is to a backlight module made by a plurality of LEDs used to be the vertical backlight source of the liquid crystal panel (LED) display. 
         [0012]    According the objects describe above, the present invention discloses a light emitting diode (LED) with longitudinal package structure comprising a carrier substrate, a LED, a first transparent substrate, a second transparent substrate, a plurality of connecting elements and a light focusing mask. The carrier substrate includes a first surface and a second surface, and a plurality of through holes pass through the first surface and the second surface and each of the though holes is filled with the conductive material. The LED includes an N electrode and a P electrode disposed at two sides of a semiconductor layer. The first transparent substrate includes a first metal layer disposed thereon, and the metal layer is electrically connected to the N electrode of the LED and the conductive material of the first surface of the carrier substrate. The second transparent substrate includes a second metal layer disposed thereon, and the second metal layer is electrically connected to the P electrode of the LED and the other conductive material of the first surface of the carrier substrate. The connecting elements are electrically connected to the conductive materials of the second surface of the carrier substrate. The light focusing mask is used to cover the first surface, the LED, the first transparent substrate and the second transparent substrate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a sectional view showing a light emitting diode (LED) structure. 
           [0014]      FIG. 2  is a view showing a carrier substrate used in the present invention 
           [0015]      FIG. 3A  is a top view showing the transparent carrier substrate used in the LED package structure in the present invention. 
           [0016]      FIG. 3B  is a sectional view of  FIG. 3A . 
           [0017]      FIGS. 4A-4B  are views showing a stacked LED with sandwich structure. 
           [0018]      FIG. 5A  is a top view showing the carrier substrate shown in the present invention. 
           [0019]      FIG. 5B  is a sectional view showing the carrier substrate shown in the present invention. 
           [0020]      FIG. 6A  is a sectional view showing the LED with sandwich structure is going to electrically connect to the carrier substrate. 
           [0021]      FIG. 6B  is a sectional view showing the LED with sandwich structure is electrically connected to the carrier substrate. 
           [0022]      FIG. 7  is a sectional view showing a LED with sandwich structure and a light focusing mask. 
           [0023]      FIG. 8  is a sectional view showing a plurality of LEDs with sandwich structure and a light focusing mask. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0024]    The following detailed description of the present invention describes a light emitting diode package structure necessary to provide an understanding of the present invention, but does not cover a complete structure composition and the operating theory. The portions relating to the conventional techniques are briefly described, and the parts of the drawings are not proportionally drafted. While embodiments are discussed, it is not intended to limit the scope of the present invention. Except expressly restricting the amount of the components, it is appreciated that the quantity of the disclosed components may be greater than that disclosed. 
         [0025]    Please referring to  FIG. 1 , it is a sectional view showing a light emitting diode (LED) structure. The LED structure  20  includes a substrate  201 , an epitaxy stacked layer  203 , a transparent conductive layer  205 , an electrode  207 . The epitaxy stacked layer  203  is formed on the substrate  201 . The transparent conductive layer  205  is formed on the epitaxy stacked layer  203 . The electrode  207  is formed on the transparent conductive layer  205  and the electrode  209  is disposed below the substrate  201 . It should be noted that the LED package structure in the present invention can be used in red light LED, green light LED, blue light LED, white light LED and so on. The LED using the package structure shown in  FIG. 1  should be included in the present invention. Besides, in order to increase the extraction efficiency of the LED, there are some openings disposed on the electrode  207  and the electrode  209 . Therefore, the light generated by LED  20  can be emitted to increase the strength of the illumination. 
         [0026]    Now referring to  FIG. 2 , it is a carrier substrate  10  used in the present invention. As shown in  FIG. 2 , the carrier substrate  10  includes a first surface, a second surface and a plurality of thought holes  12  cutting across the first surface and the second surface. The through holes are formed by the method of micro drilling. Then, there is an electroplate layer  121 / 122  formed near each of the through hole  12 . After the package process described above, the carrier substrate  10  is in the solder pot, then each of the through holes is filled with solder. It should be noted that the electroplate layer  121 / 122  in the present invention is formed as an extensional portion in two sides of the through hole on the top surface and the bottom surface of the carrier substrate  10 . The extensional electroplate layer  121  on the top surface of the carrier substrate  10  is used to be the reflective layer of the LED. The extensional electroplate layer  122  on the bottom surface of the carrier substrate  10  is used to be the connecting point of the LED and the connecting interface for thermal fin. The carrier substrate  10  is packaged as the common circuit, so the detailed package process is omitted. 
         [0027]    Now please referring to  FIG. 3A  and  FIG. 3B , those are the top view and the sectional view of the transparent carrier substrate used in the LED package structure in the present invention. As shown in  FIG. 3A , a plurality of standalone metal layers with equal size are disposed on the transparent substrate  30 / 32 . The method of forming the metal layer is: forming a metal layer on the transparent carrier substrate  30 / 32 ; coating a photoresist layer on the metal layer and exposed by a patterning mask; removing a portion of the metal layer by eroding method; after removing a portion of the photoresist layer, a plurality of standalone metal layers with equal size are formed on the transparent carrier substrate  30 / 32 . In addition, the size of the metal layer is little bigger than the LED  20 . 
         [0028]    Besides, the step of forming the metal layers  300  on the transparent carrier substrate  30 / 32  includes: coating the photoresist layer on the transparent carrier substrate  30 / 32 ; forming a concave or channel on the photoresist layer after exposing and developing by a patterning mask; filling the metal material in the concave or channel and removing the photoresist layer to form the metal layer  300  on the transparent carrier substrate  30 / 32 . It should be noted that each of the metal layer  300  alternatively includes an opening, which is corresponding to the opening on the electrode  207 / 209  of the LED  20 . The metal material  300  in the present invention is formed by evaporating process or sputtering process. But in the preferred embodiment, the metal material is formed by plating. 
         [0029]    Please referring in  FIG. 4A , it is a stacked LED with sandwich structure. First of all, the packaged LED  20  was cut into an individual chip. The LED  20  is moved by a transferred device and the electrode  209  in each of the LED  20  is stuck on the metal layer  300  of the transparent carrier substrate  32  by conductive glue (not shown). Therefore, the electrode  209  of the LED  20  is electrically connected to the metal layer  300  of the transparent carrier substrate  32 . In the present embodiment, the conductive glue is a solder paste. After the process described above, after a suitable alignment step, the transparent carrier substrate  30  is stuck on the other electrode  207  in each of the LED  20 . Similarity, the electrode  207  of the LED  20  is electrically connected to the metal layer  300  of the transparent carrier substrate  30 , as shown in  FIG. 4A . 
         [0030]    Because the size of the metal layer  300  on the transparent carrier substrate  30 / 32  is bigger than the electrode  207 / 209  of the LED  20 , a portion of the metal layer  300  on the transparent carrier substrate will be cut when the LED  20  is cut by following the sawing line  101  shown in  FIG. 4A . After the sawing step for the transparent carrier substrate  30 / 32  was done, a few of LEDs with sandwich structure were formed. And the exposed metal layers  300  are disposed on the two sides of each of the LED  20  with sandwich structure, as shown in  FIG. 4B . 
         [0031]    Now referring to  FIG. 5A  and  FIG. 5B , those are the top view and the sectional view of the carrier substrate shown in  FIG. 2 . As shown in  FIG. 5A , the carrier substrate  10  includes a first surface, a second surface and a plurality of thought holes  12  cutting across the first surface and the second surface. The through holes are filled with conductive material, such as solder, which is used to be a connecting point. Each of the through hole  12  is disposed on the edge of the first surface and the second surface and includes an extensional electroplate layer  121 / 122 . The exposed end of the metal layer  300  of the LED  200  with sandwich structure is electrically connected to the connecting pairs  110  of the carrier substrate  10 . As shown in  FIG. 6A , obviously, each of the LED  20  with sandwich structure is vertically raised to electrically connect to the connecting point. A plurality of connecting elements  40 , such as solder bump or metal lead, are formed on the connecting points of the second surface of the carrier substrate  10 , as shown in  FIG. 6B . 
         [0032]    When the connecting element  40  is electrically connected to a power source, the LED  20  will generate light. The light generated by LED  20  can pass through the two sides of the transparent carrier substrate  30 / 32  to illuminate. Because the LED  20  with sandwich structure in the present invention is vertically packaged, the illumination of the LED  20  is covered by the electrode is reduced and the extraction efficiency of the LED  20  is enhanced. 
         [0033]    Before the sawing step, the package process in the present invention can cut the LED  20  with sandwich structure into individual packaged element in accordance with customers&#39; request or a few of LEDs with sandwich structure and equal size. The connecting points in the carrier substrate  10  are connected to let the LEDs with sandwich structure illuminate evenly. Because the connecting method described above is well known, it is not necessary to describe more detail. Besides, it should be noted that the main part of the LED  20  is packaged as a sandwich structure in accordance with the transparent carrier substrate  30 / 32  in the embodiment of the present invention. Therefore, when the LED  20  with sandwich structure is cut, it is not necessary to use some resins to protect to have illumination function. 
         [0034]    However, in order to let the LED  20  with sandwich structure generate high illuminative light, there is a light focusing mask  50  is added near the LED  20  in the present invention. There is a reflective layer (not shown) disposed on the internal side of the light focusing mask  50  and forms a better light reflective path in accordance with the extensional electroplate layer  121  on the first surface of the carrier substrate  10  to increase the illuminative efficiency. It should be noted that the method to add the light focusing mask  50  in the present invention is like the normal package method of the conventional LED. After each of the Led is cut into an individual chip, the light focusing mask is added one after another. The method to add the light focusing mask is by sticking way or molding by a fasten element, it is not limited in the present invention. The material of the light focusing mask in the present invention is plastic material but is not limited. After the structure shown in  FIG. 6B  was done, the light focusing mask  50  is stuck or molded to cover each of the LED  20  with sandwich structure, as shown in  FIG. 7 . Obviously, the method described above is able to avoid the LED  20  with sandwich structure being polluted. Because the reflective layer (not shown) is disposed on the internal side of the light focusing mask  50  to have a better light reflective path in accordance with the extensional electroplate layer  121  of the first surface of the carrier substrate  10  to increase the illuminant efficiency. 
         [0035]    When the light focusing mask  50  is stuck or molded to cover the LED  20  with sandwich structure, the single LED  20  with sandwich structure is shown in  FIG. 7 . And there is a plurality of LEDs  20  with sandwich structure shown in  FIG. 8 . The final step is to cut the LED package structure by following the sawing line  101 , the package structure of the present invention is done. It should be noted that the light focusing mask  50  can be formed a semi-sphere shape, as shown in  FIG. 7  and  FIG. 8 . However, in different embodiment, the light focusing mask  50  can be formed a different geographic shape. Especially, when the LED  20  with sandwich structure is used to be a illuminative source or backlight source, the light focusing mask  50  is formed a plate structure. 
         [0036]    Obviously, when the package structure of the present invention shown in  FIG. 8  is used to connect with a power source device, it is formed a vertical backlight module. Therefore, when the backlight module of the present invention is connected to a liquid crystal panel (LCD) (not shown), the package structure is used in a LCD display. At the time, the light focusing mask  50  with plate structure is used to reduce the thick of the backlight module. In addition, when the LEDs  20  with sandwich structure shown in  FIG. 8  is consist of at least one red light LED, at least one green light LED and at least one blue light LED, it is formed an light source. 
         [0037]    Although specific embodiments have been illustrated and described, it will be appreciated by those skilled in the art that various modifications may be made without departing from the scope of the present invention, which is intended to be limited solely by the appended claims.