Patent Publication Number: US-2013234184-A1

Title: Light emitting diode package and method of manufacturing the same

Description:
BACKGROUND 
     1. Technical Field 
     The disclosure relates to light emitting diode (LED) packages, and particularly to an LED package with high heat dissipating capability and a method of manufacturing the LED package. 
     2. Discussion of Related Art 
     LEDs&#39; many advantages, such as high luminosity, low operational voltage, low power consumption, compatibility with integrated circuits, easy driving, long term reliability, and environmental friendliness have promoted their wide use as a lighting source. 
     Generally, an LED package includes an LED chip and an encapsulant arranged on the light emitting surface of the LED chip with fluorescent doped thereof. The encapsulant is formed by adhesive injection. However, it is difficult to control the height and the shape of the encapsulant via adhesive injection; as a result, the light emitted by the LED chip has a yellow halo and an uneven illumination. 
     Therefore, what is needed is an LED package which can overcome the described limitations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a schematic, cross-sectional view of an LED package according to an exemplary embodiment of the present disclosure. 
         FIGS. 2 to 7  are cross-sectional views showing different steps of an embodiment of a method for manufacturing the LED package of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     Referring to  FIG. 1 , an LED package  10  in accordance with an exemplary embodiment of the present disclosure is illustrated. The LED package  10  includes a substrate  12 , an LED chip  14 , a fluorescent layer  16  surrounding and covering the LED chip  14  and an encapsulant  18  surrounding and covering the fluorescent layer  16 . 
     In the present embodiment, the substrate  12  is a rectangular plate and can be made of ceramic or silicon (Si). The substrate  12  includes a top surface  120   a  and a bottom surface  120   b  opposite to the top surface  120   a . The substrate  12  has a first electrode  122  and a second electrode  124  formed thereon. The first electrode  122  and the second electrode  124  extend from the top surface  120   a  of the substrate  12  to the bottom surface  120   b  thereof along an outer edge of the substrate  12 , whereby the LED package  10  is formed as a surface mounting type device. 
     The LED chip  14  is mounted on the first and second electrodes  122 ,  124  via a flip-chip technology. The LED chip  14  has a planar upper surface  142  away from the first and second electrodes  122 ,  124 , and a side surface  144  perpendicular to the upper surface  142 . In other embodiments, the LED chip  14  can be mounted on the first electrode  122  or the second electrode  124  via wire bonding. 
     The fluorescent layer  16  coats the upper surface  142  and the side surface  144  of the LED chip  14 . The fluorescent layer  16  includes a first surface  161  away from the substrate  12  and an outer side surface  160  perpendicular to the first surface  161 . In the present embodiment, the fluorescent layer  16  is evenly distributed over the LED chip  14 . 
     A distance between the first surface  161  of the fluorescent layer  16  and the upper surface  142  of the LED chip  14  is equal to a distance between the outer side surface  160  and the side surface  144  of the LED chip  14 . 
     The encapsulant  18  is arranged on the top surface  120   a  of the substrate  12  and covers the fluorescent layer  16  and part of the first and second electrodes  122 ,  124 . The encapsulant  18  is formed of solidified silicone. In the present embodiment, a side surface of the encapsulant  18  is coplanar with an outer side surface of the first and second electrodes  122 ,  124 , and a top surface of the encapsulant  14  is planar. 
     The fluorescent layer  16  is evenly distributed over the LED chip  14 ; therefore, the light color and the light emission of the LED package  10  can be substantially evenly distributed. 
     Referring to  FIGS. 2-7 , a method for manufacturing the LED package  10  in accordance with an exemplary embodiment is also disclosed. The method includes the following steps. 
     Step 1: referring to  FIG. 2 , a substrate  12  is provided, wherein the substrate  12  includes a top surface  120   a  and a bottom surface  120   b  opposite to the top surface  120   a . In the present embodiment, the substrate  12  includes two first electrodes  122  and two second electrodes  124  formed thereon. Each first electrode  122  and each second electrode  124  extend from the top surface  120   a  of the substrate  12  to the bottom surface  120   b  thereof, whereby the LED package  10  is formed as a surface mounting type device. 
     Step 2: referring to  FIG. 3 , two LED chips  14  are respectively mounted on the first and second electrodes  122 ,  124  via a flip-chip technology. The LED chip  14  has a planar upper surface  142  away from the corresponding first and second electrodes  122 ,  124 , and a side surface  144  perpendicular to the upper surface  142 . In other embodiments, the LED chip  14  can be mounted on the first electrode  122  or the second electrode  124  via wire bonding. 
     Step 3: referring to  FIG. 4 , a fluorescent layer  16  is formed on the top surface  120   a  of the substrate  12  and covers the LED chips  14  and part of the first and second electrodes  122 ,  124 . In the present embodiment, the fluorescent layer  16  has a planar first surface  161  away from the substrate  12 , and a height of the fluorescent layer  16  is larger than that of the LED chip  14 . A distance between the upper surface  142  of the LED chip  14  and the first surface  161  of the fluorescent layer  16  is H. 
     Step 4: referring to  FIG. 5 , a patterned mask  15  and an ultraviolet light source  17  is provided. The patterned mask  15  has a plurality of through holes  151  formed therein. The patterned mask  15  is arranged on the first surface  161  of the fluorescent layer  16 . The fluorescent layer  16  includes first parts  164 , each of which is just located above and surrounds an LED chip  14 , and second parts  165  each of which is deviated from the corresponding LED chip  14  and connected to the first parts  164 . Each of the first parts  164  is exposed to a corresponding through hole  151  of the patterned mask  15 . In the present embodiment, each first part  164  of the fluorescent layer  16  has an outer side surface  1641 , and a distance between the outer side surface  1641  of the first part  164  and the side surface  144  of the corresponding LED chip  14  is A. In the present embodiment, the distance A is equal to the distance H. The ultraviolet light source  17  irradiates through the through holes  151  of the patterned mask  15  to secure the first parts  164  of fluorescent layer  16 . 
     Step 5: referring to  FIG. 6  also, the patterned mask  15  and the ultraviolet light source  17  are removed, and the second parts  165  of the fluorescent layer  16  are removed. In the present embodiment, the second parts  165  of the fluorescent layer  16  are removed via etching. The substrate  12 , the LED chip  14 , and the fluorescent layer  16  are submerged into solution, such as n-Heptanes, Toluene, Acetone and so on. The second parts  165  of the fluorescent layer  16  are not irradiated by the ultraviolet light source  17 ; thus, the second parts  165  of the fluorescent layer  16  dissolve in the solution and separated from the substrate  12 . The first parts  164  of the fluorescent layer  16  are irradiated by the ultraviolet light source  17  and are firmly arranged on the corresponding LED chip  14 . Since the distance A between the outer side surface  1641  of the first part  164  and the corresponding side surface  144  of each the LED chip  14  is equal to the distance H between the upper surface  142  of the LED chip  14  and the corresponding first surface  161  of the fluorescent layer  16 , the first parts  164  of the fluorescent layer  16  acts as a conformal coating mounted on the surrounding of the corresponding LED chip  14 . 
     Step 6: referring to  FIG. 7 , an encapsulant  18  is arranged on the top surface  120   a  of the substrate  12  and covers the first parts  164  of the fluorescent layer  16  and parts of the first and second electrodes  122 ,  124 . In the present embodiment, the substrate  12  is incised to form two LED packages  10 , and the side surface of the encapsulant  14  is coplanar with the outer side surface of the first and second electrodes  122 ,  124 . 
     It is to be further understood that even though numerous characteristics and advantages have been set forth in the foregoing description of embodiments, together with details of the structures and functions of the embodiments, the disclosure is illustrative only; and that changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.