Abstract:
A method for manufacturing a light emitting diode is disclosed. Firstly, two leads each including a plateau are provided. A blocking layer is then formed on each plateau. A base is molded on the leads to embed the two leads therein, wherein the two blocking layer are exposed from the base. The blocking layers are removed from the plateaus so that the two plateaus are exposed. A light emitting chip is bonded on one plateau with a wire connecting the chip with the other plateau. Finally, an encapsulant is formed on the base to seal the chip and the wire.

Description:
BACKGROUND 
       [0001]    1. Technical Field 
         [0002]    The present disclosure relates to methods for manufacturing light emitting devices, and more particularly, to a method for manufacturing an LED (light emitting diode) and an LED obtained by the method. 
         [0003]    2. Description of Related Art 
         [0004]    As a new type of light source, LEDs are widely used in various applications. An LED often includes a base, a pair of leads formed in the base, a light emitting chip mounted on the base and electrically connected to the leads, and an encapsulant sealing the chip. Generally, each lead is embedded in the base with a top end exposed on a top face of the base and a bottom end exposed on a bottom surface of the base. The top end of each lead has an exposed top surface electrically connected to the chip through wires or other methods, and the bottom end of each lead has an exposed bottom surface electrically connected to external electrical structures such as a printed circuit board. 
         [0005]    The base is typically molded on the leads by injection molding. However, during the injection molding, burrs may be formed on the exposed top surfaces of the top ends of the leads due to an engagement between the mold for the injection molding and the exposed top surfaces of the top ends of the leads. Such burrs will affect normal electrical contact between the top ends of the leads and the wires, thereby jeopardizing the quality of the LED. Furthermore, the top ends of the leads are all flat with bottom faces thereof engaging with the base only. Such engagement sometimes is insufficient to hold the leads to the base, whereby the top ends of leads may warp after a period of use due to internal stress and separate from the base. This also will affect the quality of the LED. 
         [0006]    What is needed, therefore, is a method for manufacturing an LED and an LED obtained thereby which can overcome the limitations described above. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0007]    Many aspects of the present 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. 
           [0008]      FIG. 1  shows a first step of a method for manufacturing an LED in accordance with an embodiment of the present disclosure. 
           [0009]      FIG. 2  shows a second step of the method for manufacturing the LED in accordance with the embodiment of the present disclosure. 
           [0010]      FIG. 3  shows a third step of the method for manufacturing the LED in accordance with the embodiment of the present disclosure. 
           [0011]      FIG. 4  shows a fourth step of the method for manufacturing the LED in accordance with the embodiment of the present disclosure. 
           [0012]      FIG. 5  shows a fifth step of the method for manufacturing the LED in accordance with the embodiment of the present disclosure. 
           [0013]      FIG. 6  shows a sixth step of the method for manufacturing the LED in accordance with the embodiment of the present disclosure. 
           [0014]      FIG. 7  shows a top view of  FIG. 6 . 
           [0015]      FIG. 8  shows a seventh step of the method for manufacturing the LED in accordance with the embodiment of the present disclosure. 
           [0016]      FIG. 9  shows the LED obtained by the present disclosure, which has been manufactured after the steps of  FIGS. 1-8 . 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0017]    Referring to  FIGS. 1-9 , a method for manufacturing an LED  100  in accordance with an embodiment of the present disclosure is shown. The method mainly includes several steps as discussed below. 
         [0018]    Firstly, two leads  11 ,  12  are provided as shown in  FIG. 1 . The two leads  11 ,  12  are separated from each other. Each of the two leads  11 ,  12  includes a bottom section  114 ,  124 , a top section  112 ,  122  above the bottom section  114 ,  124  and a middle section  110 ,  120  interconnecting the bottom section  114 ,  124  and the top section  112 ,  122 . The top section  112 ,  122  of each lead  11 ,  12  is stamped to have a plateau  15 ,  16  protruding upwardly and two inclined portions  13 ,  14  connected to two opposite ends of the plateau  15 ,  16 . The plateau  15 ,  16  is parallel to the bottom section  114 ,  124  and perpendicular to the middle section  110 ,  120 . The plateau  16  of the top section  122  of a right lead  12  has a size smaller than the plateau  15  of the top section  112  of a left lead  11 . 
         [0019]    As shown in  FIG. 2 , two blocking layers  17 ,  18  are formed on the two plateaus  15 ,  16  of the two leads  11 ,  12 , respectively. The two blocking layers  17 ,  18  may be made of photoresist or polymer compound materials. Each blocking layer  17 ,  18  wholly covers a top face of the plateau  15 ,  16  of a corresponding top section  112 ,  122 . The other parts of the corresponding top section  112 ,  122  are exposed outside each blocking layer  17 ,  18 . Each blocking layer  17 ,  18  has two inclined sides coincidental with the two inclined portions  13 ,  14  of the corresponding top section  112 ,  122 . 
         [0020]    As shown in  FIG. 3 , a mold unit  20  is provided. The mold unit  20  includes a first mold  22  and a second mold  21  separated from the first mold  22 . The first mold  22  is located above the two leads  11 ,  12 , and the second mold  21  is located below the two leads  11 ,  12 . The first mold  22  defines an annular groove  24  and two recesses  27 ,  28  in a bottom face thereof. The two recesses  27 ,  28  are surrounded by the annular groove  24 . The two recesses  27 ,  28  are located corresponding to the two plateaus  15 ,  16  of the two leads  11 ,  12 , and the annular groove  24  is located generally corresponding to the two middle sections  110 ,  120  of the two leads  11 ,  12 . Each recess  27 ,  28  has a depth larger than a thickness of a corresponding blocking layer  17 ,  18 , and the annular groove  24  has a depth larger than that of the two recesses  27 ,  28 . The second mold  21  defines a large chamber  23  in a top face thereof. The chamber  23  has a depth equal to a height of each lead  11 ,  12  so that the two leads  11 ,  12  can be substantially totally received in the chamber  23 . The second mold  21  has a horizontal inner face  230  defining a bottom of the chamber  23  and a plurality of vertical inner faces  232  defining laterals of the chamber  23 . 
         [0021]    As shown in  FIG. 4 , the first mold  22  and the second mold  21  are brought to move towards each other until the first mold  22  and the second mold  21  join together. The two leads  11 ,  12  are completely received in the chamber  23  of the second mold  21 , and the two blocking layers  17 ,  18  are totally received in the two recesses  27 ,  28 , respectively. The bottom sections  114 ,  124  of the two leads  11 ,  12  abut against the horizontal inner face  230  of the second mold  21 , and the middle sections  110 ,  120  of the two leads  11 ,  12  abut against the vertical inner faces  232  of the second mold  21 . A molding material  300  is injected into the chamber  23 . The molding material  300  fills the chamber  23  and the annular groove  24 . The two recesses  27 ,  28  are blocked by the two blocking layers  17 ,  18  so that no molding material  300  enters the two recesses  27 ,  28 . The molding material  300  engages an entirety of the top sections  112 ,  122  of the leads  11 ,  12 , except the top surfaces of the plateaus  15 ,  16 , which are covered by the blocking layers  17 ,  18 . The molding material  300  is then cured to harden to form a base  30  (see  FIG. 5 ). The molding material  300  filling the annular groove  24  forms an annular sidewall  36  (see  FIG. 5 ) on a top face of the base  30 . The annular sidewall  36  surrounds the two blocking layers  17 ,  18 . The annular sidewall  36  forms a reflective cup for the LED  100 . Reflective material such a silver film can be coated on an inner surface of the annular sidewall  36 . 
         [0022]    The first mold  22  and the second mold  21  are removed from the two leads  11 ,  12  as shown in  FIG. 5 . The two blocking layers  17 ,  18  are exposed out of the base  30 . 
         [0023]    As shown in  FIGS. 6-7 , the two blocking layers  17 ,  18  are then removed from the two plateaus  15 ,  16  via etching, radiation or other suitable methods. The two plateaus  15 ,  16  are thus exposed from the base  30 . Since the top faces of the two plateaus  15 ,  16  are covered by the two blocking layers  17 ,  18  during injection of the molding material  300  and do not have any engagement with the mold unit  20 , burr cannot formed on the top faces of the two plateaus  15 ,  16 . Thus, the top faces of the two plateaus  15 ,  16  can keep intact after removing the two blocking layers  17 ,  18 . 
         [0024]    A light emitting chip  40  is attached on a larger plateau  15  as shown in  FIG. 8 . The attachment of the chip  40  to the top face of the larger plateau  15  may be achieved by electrically-conductive materials such as silver adhesive. The chip  40  is further electrically connected to a smaller plateau  16  through a wire  41 . Since the top faces of the two plateaus  15 ,  16  are intact, the electrical connection between the chip  40  and the two plateaus  15 ,  16  can be optimal. 
         [0025]    Finally, an encapsulant  50  is formed in the base  30  to be surrounded by the annual sidewall  36  and seal the chip  40  and the wire  41  as shown in  FIG. 9 . The encapsulant  50  is transparent so that light emitted from the chip  40  can pass through the encapsulant  50  to an outside environment. Phosphors (not shown) may be further doped within the encapsulant  50  to change color of the light emitted from the chip  40 . 
         [0026]    It is believed that the present disclosure and its advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the present disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments.