Abstract:
A method for packaging a light emitting diode is provided. The steps comprise: providing a material; drying the material; feeding the material into a feeding inlet; and providing a mold with pre-embedded light diodes. The material enters the feeding inlet and is injected into the mold by pressing a screw, allowing the material to combine with the light emitting diode.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a method for packaging a light emitting diode, and in particular, to a method utilizing the technique of injection molding. 
     2. Description of the Related Art 
     The conventional method for packaging a light emitting diode is accomplished by epoxy infusion, packaging epitaxy chips pre-embedded in a mold. Epoxy, thermosetting polymer, requires a curing process after entering the mold during the packaging process, resulting in decreased packaging rate. Additionally, when epoxy is cured, it is not recyclable and therefore waste material produced during the packaging process cannot be fully utilized. Moreover, after epoxy is cured, the products require aid of a mold release agent to be released from the mold. The products are formed with burr that an extra trimming procedure is necessitated. Further, epoxy has a transmission rate of merely 80% and it doesn&#39;t comprise desirable UV resistance. At last, epoxy contains corrosive chlorine which can damage the chips packaged therein. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention provides a method for packaging a light emitting diode. The steps comprise: providing a material; drying the material; feeding the material into a feeding inlet; and providing a mold with pre-embedded light diodes. The material enters the feeding inlet and is injected into the mold by pressing a screw, allowing the material to combine with the light emitting diode. 
     A detailed description is given in the following embodiments with reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein: 
         FIG. 1  is a flowchart showing the method for packaging a light emitting diode of the invention; 
         FIG. 2  is a schematic view of a mold of the invention; and 
         FIG. 3  is a schematic view of a guiding rack with light emitting diodes. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-3 , a method for packaging a light emitting diode of the invention is completed by injection molding, in which a material is pressurized in a mold, allowing the material to combine with a light emitting diode. 
     Referring to  FIG. 1 , firstly, a material is provided (as shown in step A). The material is a high polymer comprising the characteristics of thermoplastic, climate resistance, UV resistance and duration. The transparency of the material is greater than 80%, the heat resistance of the material is greater than 100° C., and absorptivity of the material is less than 0.5 wt %. For example, the material is polymer, acrylic, copolymer or combination thereof. Next step, the material is dried in 120° C. for three hours (as shown in step B), and fed into a feeding inlet (as shown in step C). 
     Referring to  FIG. 2 , a mold  100  is provided (as shown in step A 1 ). The mold  100  comprises an upper part  110  and a lower part  120 . The upper part  110  comprises ten passages  111 . Twenty recesses S are formed between the upper part  110  and the lower part  120 , wherein each passage  111  communicates with two recesses S. 
     Referring to  FIG. 3 , a guiding rack  200  is provided (as shown in step B 1 ). The guiding rack  200  comprises a plurality of guiding wires  201 , and twenty light emitting diodes L are disposed at ends of the guiding wires, respectively (as shown in step C 1 ). The guiding rack  200  is disposed in the mold  100 , and the twenty light emitting diodes L are correspondingly disposed in the recesses S (as shown in step D 1 ). 
     Referring to  FIG. 1  again, in step E, the material, entering the feeding inlet, is injected into the mold  100  by a screw with a diameter of 45 mm at a pressure of 100-200 Kg/cm 2 . Temperature of the material is set to 265° C. at the feeding inlet, and 270° C. when it is injected into the mold. It should be noted that 265° C. is set to be the material temperature at the feeding inlet, and 275° C. is set to be the material temperature when the material is injected, but it is not limited thereto. According to the characteristics of different material, the material temperature at the feeding inlet can be set at 10° C.-30° C. above the melting point, and the material temperature during the injection can be set at 15° C.-35° C. above the melting point. At last, the material entering the mold  100 , flows into the recesses S through the passages  111  of the upper part  110 , allowing the material to combine with the light emitting diodes L, therefore packaging the light emitting diodes L therein (as shown in step F). 
     Table 1 shows the comparison between the method of the invention and the conventional method for packaging. The invention utilizes polyethylene terephthalate (PET) and the conventional method utilizes epoxy resin. Molecular formulas are as follow: 
                                
As shown in table 1, the PET injection molding of the invention for packaging the light emitting diodes comprises less injection time, curing time and packaging period. Additionally, post curing time and the cleaning of the mold can be eliminated, and a mold release agent is not required to help remove the products from the mold. The product is formed without burr, such that trimming process of the burr can be saved, saving costs and time. The use of thermoplastic material for LED packaging characterizes high transparency, high heat resistance, high refraction, high UV resistance and low absorptivity. It is also recyclable, saving material costs and protecting the environment at the same time.
 
     
       
         
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                   
                 Epoxy 
               
               
                   
                 Pet injection molding 
                 infusion 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 Material 
                 Injection/infusion time 
                  1~5 sec. 
                  10~30 sec. 
               
               
                   
                 Curing time 
                  3~10 sec. 
                 30~180 sec. 
               
               
                   
                 Post curing time 
                   0 sec. 
                 Few hours 
               
               
                   
                 recycling 
                 yes 
                 No 
               
               
                   
                 Mold release agent 
                 Not required 
                 Necessary 
               
               
                 Formation 
                 Cleaning mold 
                 Not required 
                 Necessary 
               
               
                   
                 Packaging period 
                 15~30 sec. 
                 60~300 sec. 
               
               
                   
                 Burr production 
                 No 
                 yes 
               
               
                   
               
             
          
         
       
     
     While the invention has been described by way of example and in terms of preferred embodiment, it is to be understood that the invention is not limited thereto. To the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.