Abstract:
A replaceable light emitting diode (LED) package assembly has a separate structure and manufacturing process of the LED package. The LED die and a set of fluorescent material are located on a substrate. The fluorescent material device can be arranged selectively to match a required emission color according to the characteristic of wavelength of the LED die and not only is blended precisely to provide the required color but also reduces the rate of defects for the individual components of the assembly.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a replaceable light emitting diode package assembly, which discloses a separate structure and manufacturing process for a substrate with at least a LED die located and a set of fluorescent material respectively for achieving high yielding ratio.  
         [0003]     2. Description of Related Art  
         [0004]      FIG. 1  shows a cross-sectional view of a prior art surface mounted (SMD) light emitting diode (LED) device, which comprises a ring-shaped plastic reflective cup  13  on a substrate  11  and an LED die  14  mounted thereon. The LED die  14  connects with the substrate  11  electrically by a metal conducting leadframe  12 . The reflective cup  13  focuses and reflects the light from LED. An epoxy resin coating  15  encapsulates the LED die  14 , and a UV (ultraviolet ray) epoxy resin layer  16  is coated on the epoxy resin coating  15  for binding a hemisphere-shaped plastic rubber  17  thereon. Nevertheless, the manufacturing process of the SMD LED device in the prior art produces defects on account of the differences in physical characteristics of the used materials. An example is the displacement occurred due to the different layer materials with different coefficient of expansion in the structure of LED, and Taiwan Patent No. 560697 discloses a structure of a SMD LED to correct the fault.  
         [0005]      FIG. 2  shows another prior art SMD LED, in which a packaging glue  24  is cast on a printed circuit board (PCB)  21  directly and an extra colloid is adhered thereon as well, so that the packaging glue  24  will not fall off. Alternatively, a metal reflective cup  23  is employed to reflect and focus the light from the LED die  22  located therein.  
         [0006]     In addition to the description of the SMD LED in the previous description, yet another kind of lead-type LED structure exists, such as that disclosed by Taiwan Patent No. 564535 and shown in  FIG. 3 , which refers to a carrier  30  including a pair of leads  39  to connect with other components or the circuit board of LED. In the space of a cavity  36 , an LED die  32  is adhered on the PCB  33  by a bonding layer  38 , and the electrode  37  of LED die  32  is bonded with the electrical terminal of leads  39  by wire  35 . Furthermore, the LED die  32  is encapsulated with a fluorescent layer  34  and light-guiding packaging glue  31 .  
         [0007]     Reference is made to the prior art described in  FIGS. 1, 2  and  3  above, in which the packaging glue  24 ,  31  are formed integrally or assembled with other components outside the LED die respectively and then the fluorescent layer also envelopes the LED die for adjusting the emission color. Although the prior art described in Taiwan Patent No. 552726 provides a solution to the problem for thermal dissipation of LED, color error still occurs due to deviations in the manufacturing process and the materials of the fluorescent layer.  
         [0008]     To correct the problem in the prior art, the present invention provides a replaceable light emitting diode package assembly with a fluorescent component set for the good flexibility in the process of fabrication and solve the problem discovered after packaging in the prior art.  
       SUMMARY OF THE DISCLOSURE  
       [0009]     Broadly speaking, the invention relates to a replaceable light emitting diode package assembly, which discloses the separate manufacturing process of the LED package including a substrate the LED die located and a set of fluorescent material, respectively. The device of fluorescent material can be changed selectively, and economize the use of the fluorescent material, which is changed in accordance with requirement as desired.  
         [0010]     The assembly comprises a stand, a reflective cup set upon the stand, at least one LED chip that electronically connect with the stand and a fluorescent component set, which can be transparent and removed from the LED. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0011]     The present invention will be readily understood by the following detailed description in conjunction accompanying drawings, in which:  
         [0012]      FIG. 1  is a schematic drawing of a surface mounted device LED of the prior art;  
         [0013]      FIG. 2  is a schematic drawing of a SMD LED of the prior art;  
         [0014]      FIG. 3  is a schematic drawing of a lead-frame LED of the prior art;  
         [0015]      FIG. 4  is a schematic drawing of the first present invention embodiment of the replaceable light emitting diode package assembly;  
         [0016]      FIG. 5  is a schematic drawing of the second embodiment of the present invention;  
         [0017]      FIG. 6  is a schematic drawing of the third embodiment of the present invention;  
         [0018]      FIG. 7  is a schematic drawing of the fourth embodiment of the present invention;  
         [0019]      FIG. 8  is a schematic drawing of the fifth embodiment of the present invention; and  
         [0020]      FIG. 9  is a schematic drawing of the sixth embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0021]     One aspect of the present invention relates to a technique of combining light emitting diode (LED) components, which includes a replaceable fluorescent unit and an emitting device unit, respectively. The fluorescent unit can be made of fluorescent material or coated with fluorescent material on its surface, thus achieving a separate structure and manufacturing process for a substrate whereon the LED chip located and a set of fluorescent material.  
         [0022]     Reference is made to  FIG. 4 , which is a schematic drawing of the first embodiment of present invention. The combination of the fluorescent unit  47  and the emitting device unit  40 , which is a kind of surface mounted type (SMD) LED, is shown. The metal terminal  41   a ,  41   b  of LED is constructed on the circuit board  49 , and a first terminal  41   a  and a second terminal  41   b  are connected with the two electrodes of LED chip  45 , respectively. A reflective cup  43  with the function of focus and reflection is installed above the metal terminal, and an LED chip  45  of the emitting device unit  40  is connected with the elements of circuit board by metal reflective cup  43 . For instance, the LED chip  45  connects with the anode shown on the first terminal  41   a  by a first bonding wire  44   a , and with cathode shown on the second terminal  41   b  by a second bonding wire  44   b.    
         [0023]     As described above, one or more LED chips  45  are embedded firmly using a packaging glue  46  and then covered with the replaceable fluorescent unit  47 , the LED chips  45  are separated with fluorescent unit  47  such that a space is present there. In the replaceable light emitting diode package assembly, fluorescent unit  47  is combined with the structure in a removable way such as bonding by glue, welding by RF heating source, or assembling with a tenon structure.  
         [0024]     The fluorescent unit  47  is made of transparent material and fluorescent powder material is added on the top face thereof, bottom face thereof or interior of the fluorescent unit  47 . The luminosity or color of the LED device can be adjusted by varying the fluorescent powder composition of the fluorescent unit  47 . In the case of a white light, the LED chip  45  itself can be a blue light LED, and then collocated with yellow fluorescent unit  47  to blend their emitted light into the white light as required. The chromaticity of the white light is also adjustable in the present invention.  
         [0025]     The invention can correct problems by replacing the fluorescent unit  47  if any defect occurs during the manufacturing process, and further achieve thermal dissipation by providing a space between the fluorescent unit  47  and LED chip  45 . Additionally, the characteristic of light is also adjusted by setting different fluorescent materials near the LED chip  45 .  
         [0026]      FIG. 5  is the second embodiment of the invention; like the structure shown in  FIG. 4 , the package structure of fluorescent unit  57  and emitting device unit  40  are illustrated. The circuit board  49  is a printed circuit board (PCB), and the LED chip  45  connects with the first terminal  41   a  and the second terminal  41   b  by the first bonding wire  44   a  and the second bonding wire  44   b , respectively, and electrically connects to the circuit board  49 . Further, the reflective cup  43  set above the terminals  41   a ,  41   b , and the LED chip  45  is embedded firmly using a packaging glue  46  and again covered with a replaceable fluorescent unit  57 . The LED chip  45  is separated from the fluorescent unit  57  with a replaceable adhesive material to connect to emitting device unit  40 .  
         [0027]     The fluorescent unit  57  in the current embodiment is a transparent material with hollow hemispheric shape, and the fluorescent materials can be coated on the outer surface, inner surface or doped inside the unit for uniform light emission. The emitted light can be adjusted by adjusting the fluorescent composition of fluorescent unit  47 , especially with regard to the color temperature, and the unit is replaced as required.  
         [0028]      FIG. 6  is a third embodiment of the present invention, which introduces a double-tiered reflective cup  63  for reflecting and focusing the light emitted from LED chip  45 . As recited with regard to the first and second embodiments above, the LED chip  45  is set on a first terminal  41   a  and a second terminal  41   b  and then connects to the electrodes on the terminals  41   a  and  41   b  by a first bonding wire  44   a  and a second bonding wire  44   b . The LED chip  45  is embedded firmly using packaging glue  46 , and the emitting device unit  60  is formed with a combination of double tiered reflective cup  63  and metal terminals  41   a ,  41   b . The invention achieves the purpose of combination and replacement by a different manufacturing process of covered replaceable fluorescent unit  67  and emitting device unit  60 .  
         [0029]      FIG. 7  is a schematic drawing of a fourth embodiment of the present invention. This figure discloses the structure of a lead-type LED, which is a combination of a fluorescent unit  77  and an emitting device unit  70 , including other elements and connecting leads  71  as shown in the drawing. The leads  71  are connected with the first terminal  73   a  and the second terminal  73   b , which are the anode and cathode individually, and then the two electrodes (anode, cathode) of LED chip  74  connect to the terminals  73   a  and  73   b  by bonding wires, respectively. The LED chip  74  is set on the concave metal cup-shaped structure formed by terminals  73   a  and  73   b  for reflecting and focusing the light.  
         [0030]     Thus, the first terminal  73   a , the second terminal  73   b  and the LED chip  74  are enveloped by a package  72 , also including the terminal electrodes of pins  71  for fastening the structure. Above the LED chip  74  there is a fluorescent unit  77  made of transparent material in, for example but not limited to, a solid or hollow bomb-like shape. The fluorescent unit  77  is connected with the emitting device unit  70  using the replaceable technique of combination The outer or inner surface of the unit is coated with fluorescent material in accordance with the required luminosity and color, furthermore, the fluorescent unit  67  can be fluorescent material itself. The present invention can change the brightness or color as required by adjusting the composition and concentration of material.  
         [0031]     Just as illustrated in  FIG. 7 ,  FIG. 8  is the fifth embodiment of the invention showing the combination of fluorescent unit  87  and the emitting device unit  70 , combined with the replaceable adhesive material. The hollow or solid fluorescent unit  87  is set on the LED chip  74  and terminals  73   a  and  73   b , which are coated with fluorescent material on the outer or inner surface thereof or doped inside. In addition, the composition can be changed according to needs.  
         [0032]     Reference is made to  FIG. 9 , which shows the sixth embodiment of the invention. The LED chip  94  is set on the terminal formed with the leads  91 , which are used as an anode and a cathode, respectively, connected to the LED chip  94  by bonding wires. The emitting device unit  90  comprises the LED chip  94  and a leads  91  enveloped with package  93  and a fluorescent unit  97  is set above the emitting device unit  90  to allow easy replacement.  
         [0033]     The many features and advantages of the present invention are apparent from written description above and intended by appended claims to cover all. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact construction and operation as illustrated and described. Hence, all suitable modifications and equivalents may be resorted to as falling within the scope of the invention.