Abstract:
A light emitting diode manufacturing method introduces a transparent enclosure to improve the uniformity of coating phosphor, so as to achieve the purposes of enhancing the uniform color temperature and the light emitting efficiency. The manufacturing method is used extensively for packaging various types of light emitting diode chips and mass production.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to a light emitting diode and a manufacturing method thereof, and more particularly to a light emitting diode manufacturing method and a light emitting diode manufactured by the method capable of enhancing the uniformity of color temperature and the light emitting efficiency of a white light emitting diode device. 
         [0003]    2. Description of the Related Art 
         [0004]      FIG. 1  illustrates a schematic view of a white light emitting diode disclosed in U.S. Pat. No. 5,998,925. The white light emitting diode  1  comprises a lead frame  11 , a GaN-based light emitting diode chip  12  for emitting a light with a first wavelength, and a phosphor  13 . The phosphor  13  absorbs a part of radiation energy produced by the GaN-based light emitting diode chip  12  and emits a light with a second wavelength, so as to obtain a white light with a third wavelength mixed from first and second wavelengths. In  FIG. 1 , the phosphor  13  and the first resin are mixed to form a mixed resin  14  containing the phosphor  13 . Then the mixed resin  14  is filled into a cup of the lead frame  11  that carries the GaN-based light emitting diode chip completely cover the GaN-based light emitting diode chip  12 . A second resin  15  is then used for sealing the lead frame  11 , the GaN-based light emitting diode chip  12  and the mixed resin  14  to complete the manufacture of the white light emitting diode. Since the thickness of the mixed resin  14  filled in the cup of the lead frame can not controlled intentionally, the phosphor may be distributed uniformly. Thus the brightness of the emitted lights in different directions and the color temperature are not uniform. 
         [0005]    U.S. Pat. No. 5,959,316 discloses another a white light emitting diode device, which is illustrated in  FIG. 2 . A light emitting diode chip  22  is placed on a lead frame  21 , and then a first transparent packaging resin  23  is used to seal and cover the top of the light emitting diode chip  22 . A mixed resin  24  is provided by a phosphor mixed with a second transparent packaging resin, and then the mixed resin  24  is used for sealing and covering the first transparent packaging resin  23 . A third transparent packaging resin  25  is used for sealing and covering the mixed resin  24 . Since the first transparent packaging resin  23  is baked and dried to constitute a circular top, and therefore the mixed resin  24  containing the phosphor can be coated onto the circular top with a specific thickness to overcome the drawbacks of having the non-uniform angular distribution of color temperature of the light emitting device. The manufacturing method disclosed in the prior art involves producing the first transparent packaging resin  23 , mixed resin  24  and third transparent packaging resin  25 , and then performing an encapsulation process. The encapsulation process requires a step of baking and drying for each resin by a high temperature. Such manufacturing processes will contaminate surfaces of the resins and cause an insufficient adhesive force between resins. Further it is difficult to improve the yield rate of the manufacturing process or simplify the manufacturing process. 
         [0006]      FIG. 3  illustrates another light emitting element as disclosed in U.S. Pat. No. 6,576,488. This patent discloses a flip chip packaging method and provides a selective electrophoresis deposition technology for a phosphor to improve the uniformity of the phosphor coated onto the light emitting diode chip, so as to overcome the drawback of having a non-uniform angular distribution of color temperature. Firstly, the light emitting diode chip  32  is mounted onto a substrate  31  by a flip chip manufacturing method. An electrophoresis apparatus  34  carrying a phosphor  33  is applied with a specific voltage such that the phosphor  33  will be deposited on an exposed surface of the light emitting diode chip  32 . Since the phosphor  33  is distributed to have a uniform thickness, the uniformity of color temperature angular distribution can be improved effectively. Although the manufacturing process can improve the uniformity of color temperature angular distribution, the complexity of the chip manufacturing process and the manufacturing cost are likely to increase since the process requires various photomasks for the light emitting diode chip  32  and the substrate  31  to prevent phosphor from being deposited on a metal conductive area if the selective electrophoresis deposition process is adopted. 
         [0007]      FIG. 4  illustrates another method of producing a white light emitting device uniformly coated with a phosphor as disclosed in U.S. Patent Publication No. 20050244993. A light emitting diode chip  42  having a vertical electrode structure is provided and mounted onto a substrate  41 , and then a phosphor mixed with another suspension is provided. As the mixed solution is sprayed at the periphery of the light emitting diode chip  42 , a phosphor coating layer  43  with a uniform thickness can be formed to improve the uniformity of the color temperature angular distribution effectively. 
         [0008]      FIG. 5  illustrates another method of producing a white light emitting device uniformly coated with a phosphor as disclosed in U.S. Pat. No. 7,217,583. A light emitting diode chip  52  is provided and mounted onto a substrate  51 , and then a phosphor mixed with a mixed solution  53  of a suspension is provided and formed on the light emitting diode chip  52 . Then, the mixed solution  53  is confined and the evaporation process of the mixed solution  53  is controlled to form a phosphor coating layer  54  with a uniform thickness at the periphery of the light emitting diode chip  52  to improve the uniformity of the color temperature angular distribution effectively. 
         [0009]    Thus, there is a need to develop a new method to uniformly coat a phosphor at the periphery of a light emitting diode chip and a light emitting diode manufactured by this method to simplify the manufacture process and the cost. 
       SUMMARY OF THE INVENTION 
       [0010]    In view of the shortcomings of the prior art, a light emitting diode and a manufacturing method thereof are provided to overcome the problem of having a non-uniform color temperature angular distribution caused by a non-uniform phosphor. 
         [0011]    The light emitting diode manufacturing method, particularly a method of packaging a light emitting diode chip by a transparent enclosure, may overcome the problem of having a non-uniform color temperature angular distribution caused by a non-uniformly coated phosphor and improve the light emitting efficiency of light emitting diode device. 
         [0012]    The light emitting diode manufacturing method, particularly a method of packaging a light emitting diode chip by a transparent enclosure may further achieve the effects of simplifying the manufacturing process and reducing the cost. 
         [0013]    To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, the embodiment of this disclosure discloses a light emitting diode manufacturing method comprising the steps of: providing a lead frame; mounting at least one light emitting diode chip onto the lead frame; electrically coupling the light emitting diode chip and the lead frame; forming a transparent enclosure to enclose the light emitting diode chip; and coating a packaging resin containing a phosphor in an area having the light emitting diode chip and enclosed by the enclosure. 
         [0014]    The embodiment of this disclosure discloses a white light emitting diode, comprising a lead frame, a light emitting diode chip, a transparent enclosure and a mixed resin having a phosphor. The light emitting diode chip is mounted onto the lead frame. The transparent enclosure is provided for enclosing the light emitting diode chip. The mixed resin containing a phosphor is formed in an area enclosed by the enclosure. 
         [0015]    In summation of the description above, the light emitting diode and its manufacturing method in accordance with the present invention have one or more of the following technical effects. The light emitting diode and the manufacturing method thereof enclose the light emitting diode chip by the transparent enclosure to improve the uniformity of coating the phosphor and the light emitting efficiency of the light emitting diode device. The light emitting diode and the manufacturing method thereof enclose the light emitting diode chip by the transparent enclosure to achieve the effects of simplifying the process of uniformly coating the phosphor and reducing the manufacturing cost. 
         [0016]    It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention. 
           [0018]      FIG. 1  is a schematic view of a first conventional white light emitting diode; 
           [0019]      FIG. 2  is a schematic view of a second conventional white light emitting diode; 
           [0020]      FIG. 3  is a schematic view of a third conventional white light emitting diode; 
           [0021]      FIG. 4  is a schematic view of a fourth conventional white light emitting diode; 
           [0022]      FIG. 5  is a schematic view of a fifth conventional white light emitting diode; 
           [0023]      FIG. 6  is a schematic view of a light emitting diode in accordance with the present invention; 
           [0024]      FIGS. 7A-7C  are schematic views showing the manufacturing procedure of a light emitting diode in accordance with the present invention; and 
           [0025]      FIG. 8  is a schematic view of another light emitting diode in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0026]    Reference will now be made in detail to the preferred embodiments, examples of which are illustrated in the accompanying drawings. 
         [0027]    With reference to  FIG. 6  for a schematic view of a light emitting diode in accordance with the present invention, the manufacturing process of the light emitting diode comprises the steps of: providing a lead frame  61 , mounting a light emitting diode chip  62  onto the lead frame  61 , forming an enclosure  63  for enclosing the light emitting diode chip  62  and providing at least one mixed resin  64  containing a phosphor in the enclosure  63  to cover onto the light emitting diode chip  62 . The enclosure  63  can be formed by a spray coating method, a screen coating method, a sol-gel method, a dispensing method, a die-casting method or the like. The lead frame  61  can be made of a composite material selected from the group of a ceramic based material, an aluminum oxide based (AlO-based) material, copper, aluminum, molybdenum, tungsten, and an aluminum nitride based (AlN-based) material. The lead frame  61  further includes a bonding area  65 , an electrically connected circuit  68 , a pad  69 , and an electrode terminal  70 . In addition, the bonding area  65  can be made of a conductor, a non-conductor, or their mixture. The light emitting diode chip  62  and the enclosure  63  have a relative distance with each other. A preferred distance can be adjusted according to the size of the light emitting diode chip  62  and the lead frame  61 . The enclosure  63  is made of a transparent material, and the predetermined thickness of the mixed resin  64  disposed on the light emitting diode chip  62  can be adjusted according to the size of the light emitting diode chip  62  and the lead frame  61 . The predetermined thickness of the mixed resin  64  is not smaller than the relative distance between an edge of the light emitting diode chip  62  and the enclosure  63 . A method selected from the collection of a sputtering method, a chemical vapor deposition method, a spray coating method, a screen coating method, a vacuum evaporation method, sol-gel method, and a dispensing method, or any combination of the above is used for forming the mixed resin  64  in an area enclosed by the enclosure. The phosphor in the mixed resin  64  can be Sr 1-x-y Ba x Ca y SiO 4 :Eu 2+ F, (Sr 1-x-y Eu x Mn y )P 2+z O 7 :Eu 2+ F, (Ba,Sr,Ca)Al 2 O 4 :Eu, ((Ba,Sr,Ca)(Mg,Zn))Si 2 O 7 :Eu, SrGa 2 S 4 :Eu, ((Ba,Sr,Ca) 1-x Eu x )(Mg,Zn) 1-x Mn x ))Al 10 O 17 , Ca 8 Mg(SiO 4 ) 4 Cl 2 :Eu,Mn, ((Ba,Sr,Ca,Mg) 1-x Eu x ) 2 SiO 4 , Ca 2 MgSi 2 O 7 :Cl, SrSi 3 O 8 .2SrCl 2 :Eu, BAM:Eu, Sr-Aluminate:Eu, Thiogallate:Eu, Chlorosilicate:Eu, Borate:Ce,Tb, Sr 4 Al 14 O 25 :Eu, YBO 3 :Ce,Tb, BaMgAl 10 O 17 :Eu,Mn, (Sr,Ca,Ba)(Al,Ga) 2 S 4 :Eu, Ca 2 MgSi 2 O 7 :Cl,Eu,Mn, (Sr,Ca,Ba,Mg) 10 (PO 4 ) 6 Cl 2 :Eu ZnS:Cu,Al, (Y,Gd,Tb,Lu,Yb)(Al y Ga 1-y ) 5 O 12 :Ce, (Sr 1-x-y-z Ba x Ca y Eu z ) 2 SiO 4 , (Sr 1-a-b Ca b Ba c )Si x N y O z :Eu a  and Sr 5 (PO 4 ) 3 Cl:Eu a  or a mixture of any combination of the above. The enclosure  63  is made of a transparent material, wherein the transparent material can be a transparent resin such as transparent epoxy resin or silicon resin, or can be a material selected from the collection of silicon dioxide, glass, and an encapsulating material. To achieve the effects of the present invention, the invention provides a manufacturing process described as follows. With reference to  FIG. 7A , the light emitting diode chip  62  is mounted onto the bonding area  65  of the lead frame  61 , and then a metal lead  71  is used for connecting an anode  66  and a cathode  67  of the light emitting diode chip  62  onto a pad  69  of the lead frame. With reference to  FIG. 7B , after the step of connecting the metal lead  71 , a transparent enclosure  63  is provided to enclose the light emitting diode chip  62  to define a space  100 . The enclosure  63  can be formed by a spray coating method, a screen coating method, a sol-gel method, a dispensing method or a die-casting method. A mixed resin  64  containing a phosphor is filled up in the space  100  to complete the manufacture of the white light emitting diode concurrently featuring a uniform color temperature and a uniform angular distribution of brightness. With reference to  FIG. 7C , a step of planarizing a surface of the mixed resin  64  can be added to the procedure. In the foregoing procedure as disclosed in  FIG. 7B , the transparent enclosure  63  is disposed on the lead frame  61 , and then the light emitting diode chip  62  is mounted onto the bonding area  65  of the lead frame  61 . The transparent enclosure  63  of this preferred embodiment is made of a transparent material, and the transparent material can be a transparent resin such as transparent epoxy resin or silicon resin, or can be made of a material such as silicon dioxide, glass, and an encapsulation material. 
         [0028]    With reference to  FIG. 8  for a schematic view of a structure of another light emitting diode in accordance with the present invention, the conductive wire circuit is omitted in the figure. The manufacturing process of the light emitting diode is described as follows. A lead frame  81  is provided, and a plurality of light emitting diode chips  82  are mounted onto the lead frame  81  to form a plurality of transparent enclosures  83 , each for enclosing the light emitting diode chip  82  to define a plurality of spaces. The enclosures  83  can be formed by a spray coating method, a screen coating method, a sol-gel method, a dispensing method or a die-casting method, and then a mixed resin  84  containing a phosphor is filled up in the plurality of spaces to complete the manufacture of white light emitting diode concurrently featuring a uniform color temperature and a uniform angular distribution of brightness. A step of planarizing a surface of the mixed resin  84  can be added to the procedure. In this embodiment, the transparent enclosure  83  is made of a transparent material, and the transparent material can be a transparent resin such as transparent epoxy resin or silicon resin, or can be made of a material such as silicon dioxide, glass, or an encapsulation material. 
         [0029]    In summation of the description above, the present invention uses the transparent enclosure to enclose the light emitting diode chip to improve the uniformity of the coated phosphor and the light emitting efficiency of the light emitting diode device, and the invention further simplifies the procedure of uniformly coating the phosphor and reduces the manufacturing cost. 
         [0030]    It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.