Patent Publication Number: US-2007099316-A1

Title: LED manufacturing process

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention is related to a method for improving light emitting diode (LED) packaging efficiency, and more particularly, to a manufacturing process allowing consistent application of encapsulation material and upgrading production capacity.  
      2. Description of the Prior Art  
      As illustrated in  FIG. 1  of the accompany drawings, an LED is essentially comprised of a light emitting chip f 10  secured with an encapsulating material  40  in a carrier  20  provided with a pit  22 ; a golden plated wire  30  connects the light emitting chip  10  and two electrodes  21 ; and the chip  10  is then encapsulated with a encapsulating material  50  containing fluorescent material  51 . Accordingly, when the chip  10  is conducted, a light source of the chip  10  excites the fluorescent powder  51  in the encapsulating material  50  to emit the light in expected color.  
      Usually, the encapsulating material  50  is applied by means of injection, extension and casting method. Wherein, the injection or extension method involves having the fluorescent material and glue mixed at a given ratio to be poured into a dedicated barrel, an injection machine and a X-Y movement mechanism are used to coat the encapsulating material by dot or by line upon the lighting emitting chip. However, either method prevents precise control of the containment of the fluorescent powder thus to fail the emission of the light in expected color and easy control of the encapsulating location resulting in deviation.  
      The casting method involves having the fluorescent powder and casting cake mixed a given ratio; the mixture is them laminated into the size of the original casting cake; and the cake containing the mixture is then cast on the light emitting chip using the casting machine and dies. The casting method though allowing control of consistent amount of he encapsulating material is found with the problem of having the encapsulating material stripped from the carrier particularly when the cake has higher containment of fluorescent powder, thinner, or smaller in volume.  
     SUMMARY OF THE INVENTION  
      The primary purpose of he present invention is to provide an LED manufacturing process to correct problems found with the prior art. To achieve the purpose, the fluorescent material in smaller grains is mixed with a plastic material to become an encapsulating material to be jet printed onto the peripheral of the light emitting chip. Jet printing permits faster production and significantly upgraded production capacity while precise control over the amount of the encapsulating material by controlling the size of the nozzle and jet location to eliminate the strip off problem occurred in the casting method. 
    
    
     BRIEF DESCRIPTION OF EH DRAWINGS  
       FIG. 1  is a schematic view showing a construction of an LED of the prior art.  
       FIG. 2  is a manufacturing process flow chart of the present invention.  
       FIG. 3  is a schematic view showing a construction of a white LED of the present invention.  
       FIG. 4  is a schematic view showing a construction of jet printing of the encapsulating material from a nozzle in the present invention.  
       FIG. 5  is a perspective view of an LED produced using the manufacturing process of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIGS. 2 and 3 , an LED manufacturing process of the present invention provides a carrier  20  containing a present pit  22 ; the carrier is applied with a bonding layer  40  to secure a light emitting chip  10  in the carrier  20 ; a goldenplated wire  30  connects the light emitting chip  10  and both electrodes  21 ; and the light emitting chip  10  is then applied with an encapsulating material  50  containing fluorescent powder  51 . Accordingly, once the light emitting chip  10  is conducted, the fluorescent powder  51  in the encapsulating material  50  is excited to emit the light in expected color.  
      in a preferred embodiment of the present invention, the light emitting chip  10  is placed in the pit  22  and secured in the bonding layer  40  by baking. The golden plated wire  30  constitutes the connection between the light emitting chip  10  and both electrodes  21 . The fluorescent material  51  in smaller grains is mixed with a plastic material to become the encapsulating material  50  and jet printed by means of a nozzle onto the area above the peripheral of the light emitting chip  10 , as also illustrated in  FIG. 4 . Finally, the white LED is packed up with a transparent hood  70  to protect components inside as illustrated in  FIG. 5 .  
      The size of the nozzle  60  is adjusted depending on the size of he area to be encapsulated. The location of the nozzle  60  and the amount of the encapsulating material  50  are controlled by the location of the light emitting chip  10 . In turn, the amount of the encapsulating material  51  can be controlled by the size and the location of the nozzle to eliminate the strip off problem between the encapsulating material and the carrier due to the stress found with the casting method of the prior art.  
      Depending on the light color desired the compositions of the light emitting chip and the fluorescent material are changed. For example, when a light color closer to white effects is expected, a blue light emitting chip is used and the blue light emitting chip is then encapsulated with an encapsulating material containing yellow fluorescent material. Similarly, an encapsulating material containing red and green fluorescent powders is applied to the blue light emitting chip, and when excited, both of the red and green fluorescent powders emit red and green lights to be incorporated into the blue light emitted form the blue light emitting chip for achieving RGB mixed light effects to produce a light color with high color development performance that is approaching white light color.  
      The prevent invention provides an improved LED manufacturing process,and the application for a patent is duly filed accordingly. However, it is to be noted that the preferred embodiments disclosed in the specification and the accompanying drawings are not limiting the present invention; and that any construction, installation, or characteristics that is same or similar to that of the present invention should fall within the scope of the purposes and claims of the present invention.