Patent Publication Number: US-2007096140-A1

Title: Sealing structure for a white light LED

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to the LED (light emitting diode) field, and more particularly to a sealing structure for a white light LED.  
      2. Description of the Prior Art  
      Referring to  FIG. 1 , a conventional LED structure is illustrated and comprises a light emitting diode (LED)  10 , a light emitting element  11 , a layer of resin coating  12 , welding wires  13 , sealing resin  14 , a leading wire  15  and an inner leading wire  16 .  
      As shown in  FIG. 1 , the LED  10  is a leading type LED with leading wire  15  and inner leading wire  16 , wherein the light emitting element  11  is mounted on the coronal portion  15   a  of the leading wire  15 , the resin coating  12  containing fluorescent substances is filled in the coronal portion  15   a  to seal the light emitting element  11 .  
      However, the method of filling the coronal  15   a  and sealing the light-emitting element  11  with the fluorescent resin coating  12  has the problem that the fluorescent substances cannot be distributed evenly, causing uneven brightness and luminance of the LED  10 .  
      The present invention has arisen to mitigate and/or obviate the afore-described disadvantages.  
     SUMMARY OF THE INVENTION  
      The primary objective of the present invention is to provide a sealing structure for a white light LED that uses a well-distributed fluorescent film to provide an even white light.  
      Another objective of the present invention is to provide a sealing structure for a white light LED that can improve the acceptance rate of the sealing structure for a white light LED.  
      The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which show, for purpose of illustrations only, the preferred embodiments in accordance with the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows a conventional LED structure;  
       FIG. 2  is a cross sectional view of a sealing structure for a white light LED in accordance with a first embodiment of the present invention;  
       FIG. 3  is a perspective view of showing the cladding layer in accordance with a second embodiment of the present invention;  
       FIG. 4  is a sealing structure for a white light LED in accordance with the second embodiment of the present invention;  
       FIG. 5  is a perspective view of showing the cladding layer in accordance with a third embodiment of the present invention; and  
       FIG. 6  is a sealing structure for a white light LED in accordance with the third embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIG. 2 , a sealing structure for a white light LED in accordance with a first embodiment of the present invention is shown and generally comprises: a base  20 , a chip  22 , welding wire  23 , a cladding layer  24 , a resin  25 , a fluorescent film  26  and an optical lens  27 . The base  20  includes a substrate  201  and a printed circuit layer  202 . The printed circuit layer  202  has an electrode-welding pad  2021  and is arranged on the substrate  201 . The chip  22  is set on the surface  21  of the printed circuit layer  202 . The cladding layer  24  having a through hole  241  is also located on the surface  21  of the printed circuit layer  202 . The chip  22  is received in the through hole  241  of the cladding layer  24 . The welding wire  23  has one end connected to the chip  22  and another end connected to the electrode welding pad  2021  on the printed circuit layer  202 . The resin  25  is filled in the through hole  241  to seal the chip  22  and the welding wire  23 , and then the resin  25  is covered with the fluorescent film  26  that is located in the through hole  241 . The fluorescent film  26  is well produced with fluorescent substances well distributed. The optical lens  27  is larger than the through hole  241  and is mounted on the surface of the cladding layer  24 .  
      The sealing structure for a white light LED in accordance with this embodiment utilizes the fluorescent film having well-distributed fluorescent substances to achieve the effect of providing a well-distributed fluorescent layer which can provide an even brightness and luminance, so as to solve the uneven distribution problem of the conventional fluorescent film, improving the acceptance rate of the sealing structure.  
      For a better understanding of the present invention, its operation and function, reference should be made again to  FIG. 2 .  
      The sealing structure for a white light LED in accordance with the present invention comprises: the base  20 , the chip  22 , the welding wire  23 , the cladding layer  24 , the resin  25 , the fluorescent film  26  and the optical lens  27 . The base  20  includes the substrate  201  and the printed circuit layer  202 . The printed circuit layer  202  with the electrode-welding pad  2021  is arranged on the substrate  201 . The chip  22  is set on the surface  21  of the printed circuit layer  202 . The cladding layer  24  having the through hole  241  is also located on the surface  21  of the printed circuit layer  202 . The chip  22  is received in the through hole  241  of the cladding layer  24 . The welding wire  23  has one end connected to the chip  22  and another end connected to the electrode welding pad  2021  on the printed circuit layer  202 . The resin  25  is filled in the through hole  241  to seal the chip  22 , the welding wire  23 , and a part of the printed circuit layer  202 .  
      The fluorescent film  26  covers the resin  25  and is located in the through hole  241 , and the fluorescent film  26  is well produced with fluorescent substances well distributed, so that the fluorescent film  26  can turn the color light from the chip  22  into white light. The optical lens  27  larger than the through hole  241  is mounted on the surface of the cladding layer  24 .  
      Referring to  FIGS. 3 and 4 ,  FIG. 3  is a stereographic view of showing the cladding layer in accordance with a second embodiment of the present invention, and  FIG. 4  is a sealing structure for a white light LED in accordance with the second embodiment of the present invention. This embodiment is slightly different from the first embodiment, and the differences are described as follows:  
      As shown in  FIG. 3 , a recess  341  is formed in the cladding layer  34 , and the recess  341  has a flat bottom  3411 . Six through holes  3421 A,  3421 B,  3421 C,  3421 D,  3421 E and  3421 F are arranged in line and defined in the center of the bottom  3411  of the recess  341 . An elongated through hole  3422 A,  3422 B is defined at either side of the line of the through holes  3421 A,  3421 B,  3421 C,  3421 D,  3421 E and  3421 F.  
      The through holes  3422 A and  3422 B are adapted to receive the electrode welding pads  3021 A and  3021 B on the surface  31  of the printed circuit layer  302 , and the electrode welding pads  3021 A and  3021 B will protrude out of the through holes  3422 A and  3422 B when the cladding layer  34  is placed on the surface  31  of the printed circuit  302 .  
      As shown in  FIG. 4 , the difference of this embodiment with respect to the first embodiment as shown in  FIG. 2  is the structure and the arrangement of the cladding layer  34  and the chip  32 .  
      In this embodiment, the cladding layer  34  is located on the surface  31  of the printed circuit layer  302  in such a manner that the electrode welding pads  3021 A and  3021 B protrude out of the through holes  3422 A and  3422 B. The chip  32  is received in the through hole  3421 A of the cladding layer  24 . The welding wires  33 A and  33 B each has one end connected to the chip  32  and another end connected to the electrode welding pads  3021 A and  3021 B on the printed circuit layer  302  via the through holes  3422 A and  3422 B.  
      The resin  35  is filled in the recess  341  and the respective through holes  3421 A,  3422 A and  3422 B to seal the chip  32 , the electrode welding pads  3021 A and  3201 B, and the welding wires  33 A and  33 B. A well-distributed fluorescent film  36  is laid over the cladding layer  34  and the resin  35  and covers the recess  341 . By such arrangement, the well-distributed fluorescent film  36  can convert the colored light emitting from the chip  32  into white light. And an optical lens  37  is placed on the fluorescent film  36 .  
      The through hole  3421 A in this embodiment is described above for purposes of example only, and in fact, each of the through holes  3421 A,  3421 B,  3421 C,  3421 D,  3421 E and  3421 F is received with a chip  32 , and each chip  32  is provided with a welding wire  33 A and  33 B.  
      Referring then to  FIGS. 5 and 6 ,  FIG. 3  is a stereographic view of showing the cladding layer in accordance with a third embodiment of the present invention, and  FIG. 4  is a cross sectional view of showing the sealing structure for a white light LED in accordance with the third embodiment of the present invention. This embodiment is slightly different from the first embodiment, and the differences are described as follows:  
      As shown in  FIG. 5 , a first recess  541  with a predetermined depth is defined in the surface of the cladding layer  54 , and a second recess  542  smaller than first recess  541  is formed in the bottom  5411  of the second recess  542 . Four through holes  5431 A,  5431 B,  5431 C and  5431 D are arranged in line and defined in the center of the bottom  5421  of the second recess  542 . A rectangular through hole  5432 A and  5432 B is defined at either side of the line of the through holes  5431 A,  5431 B,  5431 C and  5431 D.  
      As shown in  FIG. 6 , two electrode welding pads  5021 A and  5021 B are arranged on the surface of the printed circuit layer  501  and are located correspondingly to the rectangular through holes  5432 A and  5432 B, and the electrode welding pads  5021 A and  5021 B will protrude out of the through holes  5432 A and  5432 B when the cladding layer  34  is placed on the surface  31  of the printed circuit  302 .  
      The chip  52  is positioned in the through hole  5431 A and is connected to the electrode welding pads  5021 A and  5021 B by the welding wires  53 A and  53 B, respectively. The resin  55  is filled in the second recess  542  and the through holes  5431 A,  5431 B,  5431 C and  5431 D, so as to seal the bottom  542 , the welding wires  53 A and  53 B, and the chip  52 .  
      A fluorescent film  56  with well-distributed fluorescent substances is placed in the first recess  541 , so that it can convert the colored light emitting from the chip  52  into white light. And an optical lens  54  larger than the first recess  541  is placed on the cladding layer, thus forming a sealing structure for a white light LED.  
      According to the respective abovementioned embodiments, the well-distributed fluorescent film can be made by vacuum suction, powder at high pressure and high temperature, or spray coating method, spraying fluorescent substances to a transparent film, the bottom of a lens or to the cladding layer. The detail process of making the fluorescent film will be omitted. The resin in the respective embodiments can be replaced with other adhesive agents.  
      To summarize, the present invention utilizes the printed circuit layer used as a carrier for carrying power to the chip, and the well-distributed fluorescent film is arranged between the optical lens and the light emitting chip, thus forming a sealing structure for a white light LED. The well-distributed fluorescent film can convert the color light emitted from the chip into even white light, so as to solve the uneven distribution problem of the conventional fluorescent film.  
      While we have shown and described various embodiments in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.