Abstract:
Disclosed herein is a method of disposing phosphor layers, which can prevent damage to phosphors and also effectively dispose phosphor layers at desired locations of Light-Emitting Diodes (LEDs) when the phosphor layers are detached and disposed at the top surfaces of the LEDs. According to an embodiment, phosphor layers fabricated by filling phosphor layer pattern holes within an area of the vertical frame with a phosphor solution are detached from the phosphor layer pattern holes by applying force downwardly or upwardly in a vertical manner.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of Korean Patent Application No. 10-2013-0114960 filed in the Korean Intellectual Property Office on Sep. 27, 2013, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Technical Field 
     The present invention relates to a method of disposing phosphor layers and, more particularly, to a method of disposing phosphor layers, which can prevent damage to phosphor and also effectively dispose phosphor layers at desired locations of Light-Emitting Diodes (LEDs) when the phosphor layers are detached and disposed at the top surfaces of the LEDs. 
     2. Description of the Related Art 
     Recently, an LED in which aluminum (Al) or lanthanide (In) has been added to gallium nitride (GaN) has been in the spotlight due to a long lifespan, low power consumption, excellent brightness, and eco-friendly factors that are not harmful to the human body as compared with conventional incandescent bulbs. In particular, an LED chip that provides white light using phosphor layers has been further in the spotlight. 
     Such an LED is being used in automotive lightings, traffic lights, and the Back Light Unit (BLU) of a liquid crystal display due to the above advantages. 
     Recently, MacAdam&#39;s Ellipse Rule was proposed as an index for evaluating whether color coordinates measured in an artificial light source are identical with color coordinates when being seen by the human eye. MacAdam&#39;s Ellipse Rule provides a four-step criteria. In the United States, an artificial light source that does not comply with three steps of MacAdam&#39;s Ellipse rule is not allowed to be sold. In order to satisfy the three steps of MacAdam&#39;s Ellipse rule, it is very important to reduce a color deviation of white light. Korean Patent Laid-Open Publication No. 10-2008-0070193 discloses a phosphor film in which a phosphor is formed on a surface of a film made of resin. In order to dispose the phosphor film at the top surface of an LED, a process of detaching or taking the phosphor film is necessary. If the phosphor film is detached or taken, it is very difficult to reduce a color deviation of white light because the phosphor is damaged or is not effectively disposed at the top surface of the LED due to electrostatic force or adhesive force between the phosphor and the film made of resin. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention has been developed keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a method of disposing phosphor layers, which can prevent damage to phosphors and also effectively dispose phosphor layers at desired locations of LEDs when the phosphor layers are detached and disposed at the top surfaces of the LEDs. 
     Technical objects to be achieved by the present invention are not limited to the aforementioned object, and other technical objects that have not been described above will become evident to those skilled in the art to which the present invention pertains from the following description. 
     In order to achieve the above object, a method of disposing phosphor layers in accordance with an embodiment of the present invention includes preparing phosphor layer fabrication equipment including a vertical frame and a plurality of phosphor layer pattern holes vertically formed to have respective phosphor layer pattern shapes in the vertical frame within an area of the vertical frame; fabricating phosphor layers by filling the plurality of phosphor layer pattern holes of the phosphor layer fabrication equipment with a phosphor layer solution including a phosphor, silicon, and a filler and baking the filled phosphor layer solution; placing an LED under the phosphor present in each of the plurality of phosphor layer pattern holes of the phosphor layer fabrication equipment in such a way as to be spaced apart from the phosphor; and vertically applying force to the phosphor present in the phosphor layer pattern hole from a top to a bottom of the phosphor so that the phosphor is detached from the phosphor layer pattern hole downwardly and vertically and placed at the top surface of the LED. 
     In the method of disposing phosphor layers in accordance with an embodiment of the present invention, in the disposing of the phosphor at the top surface of the LED, the force vertically applied to the phosphor present in the phosphor layer pattern hole from the top to the bottom of the phosphor may be transferred by an object having a flat bottom. 
     A method of disposing phosphor layers in accordance with another embodiment of the present invention includes preparing phosphor layer fabrication equipment including a vertical frame and a plurality of phosphor layer pattern holes vertically formed to have respective phosphor layer pattern shapes in the vertical frame within an area of the vertical frame; fabricating phosphor layers by filling the plurality of phosphor layer pattern holes of the phosphor layer fabrication equipment with a phosphor layer solution including a phosphor, silicon, and a filler and baking the filled phosphor layer solution; placing an upward guider under the phosphor present in each of the plurality of phosphor layer pattern holes of the phosphor layer fabrication equipment in such a way as to be spaced from the phosphor and placing a vacuum chuck over the phosphor present in the phosphor layer pattern hole in such a way as to be spaced from the phosphor; vertically applying force to the phosphor present in the phosphor layer pattern hole from a bottom to a top of the phosphor using the upward guider so that the phosphor is detached from the phosphor layer pattern hole upwardly and vertically and then placed at a bottom of the vacuum chuck; maintaining the vacuum chuck at a specific pressure or lower (e.g., a pressure from a range of approximately 10 torr to 700 torr) so that the phosphor present at the bottom of the vacuum chuck is adsorbed by the bottom of the vacuum chuck; and moving the phosphor present at the bottom of the vacuum chuck and placing the phosphor at the top surface of an LED. 
     In the method of disposing phosphor layers in accordance with another embodiment of the present invention, the upward guider may have a flat top surface. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a plan view of phosphor layer fabrication equipment that is used in methods for disposing phosphor layers in accordance with embodiments of the present invention; 
         FIG. 2  is a perspective view of phosphor layer fabrication equipment that is used in methods for disposing phosphor layers in accordance with embodiments of the present invention; 
         FIG. 3  is a perspective view showing that phosphor layers has been fabricated in the phosphor layer fabrication equipment of  FIG. 2 ; 
         FIGS. 4A and 4B  are cross-sectional views illustrating detailed steps of a method of disposing phosphor layers in accordance with an embodiment of the present invention; and 
         FIGS. 5A to 5D  are cross-sectional views illustrating detailed steps of a method of disposing phosphor layers in accordance with another embodiment of the present invention. 
     
    
    
     The following is a description of reference numerals of principal elements in the drawings:
           1000 : phosphor layer fabrication equipment     1100 : vertical frame     1200 : downward guider     1300 ,  2300 : LED     2200 : upward guider     2400 : vacuum chuck     11  to  14 ,  21  to  24 ,  31  to  34 ,  41  to  44 : phosphor layer     1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 ,  1141  to  1144 : phosphor layer pattern hole       

     DETAILED DESCRIPTION 
     Hereinafter, some exemplary embodiments of the present invention are described in detail with reference to the accompanying drawings. 
     Phosphor layer fabrication equipment  1000  used in methods for disposing phosphor layers in accordance with embodiments of the present invention, as shown in  FIGS. 1 and 2 , may include a vertical frame  1100  and a plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  vertically formed to have respective phosphor layer pattern shapes in the vertical frame  1100  within a specific area of the vertical frame  1100 . 
     The plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  can each include at least one respective pad electrode shape. More particularly, as shown in  FIGS. 1 and 2 , rectangular pad electrode shapes are formed at the upper left and upper right locations of each of the plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144 . Examples of the pad electrode shapes are pointed out at E 1  and E 2  in  FIGS. 2 and 3 . If phosphor layers are fabricated by filling the plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  with a phosphor solution, pad electrodes can be disposed at the upper left and upper right locations of the phosphor layers. 
     The pad electrode shapes do not need to be necessarily included at the upper left and upper right locations of the plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144 , as shown in  FIGS. 1 and 2 . In some embodiments, the pad electrode shapes may be included at various locations, such as upper center, lower left, upper left, lower center, lower right, upper right, locations, and any other suitable location of the plurality of phosphor layer pattern holes, if necessary. 
     Furthermore, pad electrodes are not limited to a rectangular shape, but instead can be a circle, a triangle, a pentagon, an arc, and and/or any other suitable shape. 
     The vertical frame  1100  can be made of non-transparent materials that do not transmit light. More particularly, the vertical frame  1100  can be made of non-transparent metal materials, such as aluminum or stainless steel, or other non-transparent insulating materials, such as, without limitation, silicon or silicon oxide. If the vertical frame  1100  is made of non-transparent materials that do not transmit light as described above, the phosphor layers dried in the phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  can be located at the top surface of an LED, and from there (without need for any movements or changes therefrom), a test to be described later can be effectively performed. This is because the vertical frame  1100  does not transmit light emitted from the LED. Instead, only the phosphor layers transmit the light emitted from the LED when the characteristics of light passing through the phosphor layer are tested by passing the light emitted from the LED through the phosphor layer. 
     The phosphor layers can be fabricated by filling the plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  with a phosphor solution having viscosity of about 1,000 centipoise (cP) to 300,000 cP. If the phosphor solution having the above-described viscosity is used, the yield of the phosphor layers can be stably maintained because the phosphor solution can be effectively maintained in the plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144 . 
     A method of fabricating phosphor layers using the phosphor layer fabrication equipment used in methods of disposing phosphor layers in accordance with embodiments of the present invention is described below. 
     First, the plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  is filled with a phosphor solution that includes a phosphor (for transforming light emitted from an LED into white light by varying a wavelength of the light of the LED), silicon, and a filler. 
     The top and bottom of the vertical frame  1100  (having the phosphor layer pattern holes filled with the phosphor) solution are polished. 
     Next, the vertical frame  1100  (having the phosphor layer pattern holes filled with the phosphor solution) is dried/baked at a temperature of 50° C. (degrees Celsius) to 200° C. for about 5 minutes to 100 minutes to bake the phosphor layer in the plurality of phosphor layer pattern holes. As a result, as shown in  FIG. 3 , phosphor layers  11  to  14 ,  21  to  24 ,  31  to  34 , and  41  to  44  are located in the respective phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144 . 
     As a result of the baking, the phosphor layers  11  to  14 ,  21  to  24 ,  31  to  34 , and  41  to  44  become baked (i.e. dried) in the phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144 . The characteristics of light emitted from the LED that passes through the phosphor layers  11  to  14 ,  21  to  24 ,  31  to  34 , and  41  to  44  are tested by passing the light of the LED through the phosphor layers. 
     A method of disposing phosphor layers in accordance with an embodiment of the present invention is described below. 
     First, the phosphor layer fabrication equipment  1000 , including the vertical frame  1100  and a plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  vertically formed to have respective pad electrode shapes (like as described above) in the vertical frame within a specific area of the vertical frame as described above, is prepared. 
     Phosphor layers  11  to  14 ,  21  to  24 ,  31  to  34 , and  41  to  44  are fabricated by filling the plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  of the phosphor layer fabrication equipment  1000  with the phosphor layer solution including a phosphor, silicon, and a filler, and then baking the filled phosphor layer solution as described above. 
     As shown in  FIG. 4A , an LED  1300  is placed in such a way as to be spaced apart from a phosphor  11  to  14 ,  21  to  24 ,  31  to  34 , and  41  to  44  that is present in any of the plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  of the phosphor layer fabrication equipment  1000 . In this example, phosphor  11  and phosphor layer pattern hole  1111  are used/shown. 
     As shown in  FIG. 4B , force is vertically applied to the phosphor  11  that is present in the phosphor layer pattern hole  1111  from the top towards the bottom of the phosphor  11 . As a result, the phosphor  11  is detached from the phosphor layer pattern hole  1111  downwardly and vertically and is then disposed at the top surface of the LED  1300 . The force that is vertically applied to the phosphor  11  present in the phosphor layer pattern hole  1111  from the top towards the bottom of the phosphor  11  can be transferred by a downward guider  1200  having a flat bottom. 
     A method of disposing phosphor layers in accordance with another embodiment of the present invention is described below. 
     First, the phosphor layer fabrication equipment  1000 , including the vertical frame  1100  and a plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  vertically formed to have respective phosphor layer pattern shapes in the vertical frame  1100  within anarea of the vertical frame as described above, is prepared. 
     Phosphor layers  11  to  14 ,  21  to  24 ,  31  to  34 , and  41  to  44  are fabricated by filling the plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  of the phosphor layer fabrication equipment  1000  with the phosphor layer solution including a phosphor, silicon, and a filler, and then baking the filled phosphor layer solution, as described above. 
     As shown in  FIG. 5A , an upward guider  2200  is placed under a phosphor  11  to  14 ,  21  to  24 ,  31  to  34 , and  41  to  44  that is present in any of the plurality of phosphor layer pattern hole  1111  to  1114 ,  1121  to  1124 ,  1131  to  1134 , and  1141  to  1144  of the phosphor layer fabrication equipment  1000 . In this example, phosphor  11  and phosphor layer pattern hole  1111  are used/shown. A vacuum chuck  2400  is placed over the phosphor  11  present in the phosphor layer pattern hole  1111 . 
     As shown in  FIG. 5B , the upward guider  2200  applies force to the phosphor  11  present in the phosphor layer pattern hole  1111  in a vertical direction from the bottom towards the top of the phosphor  11 . As a result, the phosphor  11  is detached from the phosphor layer pattern hole  1111  upwardly and vertically, and is then placed at the bottom surface of the vacuum chuck  2400 . The upward guider  2200  can have a flat top surface. 
     As shown in  FIG. 5C , the phosphor  11  placed at the bottom surface of the vacuum chuck  2400  is adsorbed by the bottom surface of the vacuum chuck  2400  because the vacuum chuck  2400  maintains a specific pressure or lower. Such specific pressure may be, for example, without limitation, in a range of approximately 10 torr to 700 torr. 
     As shown in  FIG. 5D , the phosphor  11  adsorbed by the bottom surface of the vacuum chuck  2400  is moved and placed at the top surface of an LED  2300 . 
     In the methods of disposing phosphor layers in accordance with embodiments of the present invention, rather than a phosphor being formed on a surface of a film made of resin, phosphor layers are fabricated by filling phosphor layer pattern holes within an area of the vertical frame with a phosphor solution. After baking, in an embodiment, the phosphor layers are detached from the phosphor layer pattern holes by applying force downwardly and vertically. In another embodiment, the phosphor layers are detached from the vertical frame by applying force upwardly and vertically and are then adsorbed using the vacuum chuck. Accordingly, in embodiments, each phosphor layer can be disposed at a desired location of the top surface of an LED without damaging the phosphor because electrostatic force or adhesive force occurring between the phosphor and the film made of resin can be effectively prevented. 
     Although the present invention has been described in connection with the preferred embodiments for illustrating the principle of the present invention, the present invention is not limited to the aforementioned constitutions and actions. 
     A person having ordinary skill in the art will appreciate that the present invention can be changed and modified in various manners without departing from the spirit and scope of the present invention. 
     Accordingly, all proper changes, modifications, and equivalents should be construed as belonging to the scope of the present invention.