Abstract:
A light emitting diode (LED) package is provided. The LED package includes a printed circuit board (PCB), an electrode pad, an LED, a wire, and first and second moldings. The electrode pad and the LED are formed on the PCB. The wire electrically connects the LED with the electrode pad. The first molding is formed on the LED and the second molding is formed on the first molding.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a light emitting diode package and a method of manufacturing the same. 
     2.Description of the Related Art 
     A light emitting diode (LED) is a semiconductor device that can realize a light source of various colors using a compound semiconductor material such as GaAs, AlGaAs, GaN, InGaN, and AlGaInP. 
     Generally, color, brightness, luminosity, etc. determine a characteristic of an LED. The characteristic of the LED is generally determined by a compound semiconductor material used in the LED, but is greatly influenced by a package structure for mounting chips. 
     In particular, as information telecommunication devices have become small-sized and slim, elements such as a resistor, a condenser, and a noise filter have become small-sized even more and been directly mounted in a printed circuit board (PCB) (a surface mount device (SMD) type). 
       FIG. 1  is a view illustrating an LED package structure according to a related art. 
     Referring to  FIG. 1 , an LED package according to a related art includes a PCB  200  having a reflective hole  202  in which an LED  210  is mounted, a reflective coating layer  201  coated with Ag in the reflective hole  202 , a cathode electrode  220  and an anode electrode  230  connected with the reflective coating layer  201 , and wires  218  connecting the LED  210  with the reflective coating layer  201 . 
     A central region of the reflective coating layer  201  is electrically cut and the reflective coating layer  201  is electrically connected with the cathode electrode  220  and the anode electrode  230 . That is, a P electrode and an N electrode of the LED  210  are electrically connected with the reflective coating layer  201  such that the P and N electrodes are connected with the cathode electrode  220  and the anode electrode  230 . 
     The cathode electrode  220  and the anode electrode  230  may be formed by solder bonding. The cathode electrode  220  and the anode electrode  230  are formed, and then a mold lens  250  is formed on the reflective coating layer  201  of the PCB  200  in order to prevent an oxidation of the wires  218 , reduce a light loss due to an air resistance, improve thermal conductivity. 
     Meanwhile, light emitted from the LED  210  is reflected a lot inside the mold lens  250 , that is, internal reflection occurs a lot inside the mold lens, decreasing the transmittance and eventually decreasing the light efficiency. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is related to a light emitting diode and a method of manufacturing the same that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
     The invention provides an LED package with an excellent light efficiency. 
     The invention provides an LED package with a simplified manufacturing method thereof. 
     The invention provides an LED package with an excellent physical stability. 
     Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. 
     The embodiment of the invention provides an LED package, comprising: a PCB; an electrode pad formed on the PCB; an LED formed on the PCB; a first molding formed on the LED; and a second molding formed on the first molding. 
     The embodiment of the invention provides an LED package comprising: a PCB; an electrode pad formed on the PCB; an LED formed on the electrode pad; a first molding formed on the LED; and a second molding formed on the electrode pad and the first molding. 
     The embodiment of the invention provides a method of manufacturing an LED package, the method comprising: forming an electrode pad on a PCB; forming an LED on the PCB; forming a first molding on the LED by a dispensing method; and forming a second molding on the first molding by a dispensing method. 
     It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principle of the invention. In the drawings: 
         FIG. 1  is a view illustrating an LED package structure according to a related art; 
         FIG. 2  is a sectional view of an LED package according to an embodiment of the present invention; 
         FIG. 3  is a flowchart illustrating a method of forming an LED package according to an embodiment of the present invention; and 
         FIG. 4  is a view illustrating a first molding and a second molding of another shape in an LED package according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     It will be understood that when an element is referred to as being ‘on’ a layer, it can be directly on the layer, and one or more intervening layers may also be present. 
     Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings. 
       FIG. 2  is a sectional view of an LED package according to an embodiment of the present invention. 
     Referring to  FIG. 2 , the present invention exemplarily illustrates a SMD type LED package manufactured using a metal core printed circuit board (MCPCB) as an LED package. 
     An LED package according to an embodiment of the present invention includes an MCPCB  1 , two electrode pads  2  formed on the MCPCB  1 , an LED  3  formed on the electrode pads  2 , two wires  4  connecting the LED  3  with the electrode pads  2 , and a first molding  6  formed outside the LED  3  and the wires  4  and a second molding  7  formed outside the first molding  6 . 
     The LED package may further include a guide unit  5  guiding the first and second moldings  6  and  7  to be easily formed. 
     The electrode pads  2  may be formed of a conductive metal material such as Ag, Au, and Cu on the MCPCB  1  and are connected with the LED  3  through the wires  4 . The two electrode pads  2  are not electrically connected, power is supplied to the LED  3  through the two wires  4 . 
     Also, the electrode pads  2  reflect light emitted from the LED  3  to increase the light efficiency. 
     Also, the LED  3  may be formed on the MCPCB  1  or may be formed on the electrode pads  2 , as illustrated in  FIG. 2 . 
     In the present invention, the LED  3  is mounted on a planar PCB. That is, the LED  3  is formed on a planar portion of the PCB, and the portion in which the LED  3  is formed and the electrode pads  2  connected with the wires  4  are on the same plane. The MCPCB  1  may be used as the PCB. 
     In the present invention, the second molding  7  is formed in a hemispheric shape. That is, an outer circumference of a contact surface between the second molding  7  and the MCPCB  1  is formed in a circular shape. 
     In particular, a maximum distance of the contact surface between the second molding  7  and the MCPCB  1 , that is, a diameter of a circle formed of the outer circumference of the contact surface is 1.6-2.4 times larger than a maximum distance between the MCPCB  1  and the second molding  7 , that is, a height of the second molding  7 . In such a condition, the light efficiency may be maximized. 
     In other words, a contact surface between the first and second moldings  6  and  7  and the MCPCB  1  is formed in a circular shape, and a diameter of the circular contact surface is formed 1.6-2.4 times larger than the height of the second molding  7 . 
       FIG. 4  is a view illustrating a first molding and a second molding of another shape in an LED package according to an embodiment of the present invention. 
     Referring to  FIG. 4 , the first molding  6  may be formed to contact the MCPCB  1  and the second molding  7  may be formed to contact only a surface of the first molding  6  without contacting the MCPCB  1 . 
     In this case, a maximum distance of a contact surface between the first molding  6  and the MCPCB  1 , that is, a diameter of a circle formed of an outer circumference of the contact surface is formed 1.6-2.4 times larger than a maximum distance between the MCPCB  1  and the second molding  7 , that is, a height of the second molding  7 . 
     In other words, the contact surface between the first molding  6  and the MCPCB  1  is formed in a circular shape, and a diameter of the circular contact surface is formed 1.6-2.4 times larger than the height of the second molding  7 . 
     Meanwhile, a jig may be used to form the second molding  7  in a hemispheric shape having a height and a diameter in the ratio of 1:1.6-2.4, but a manufacturing method using a jig is complicated. 
     Therefore, in the present invention, the first and second moldings  6  and  7  are formed by dispensing silicone of different kinds, respectively. 
     Silicone having a high strength and an excellent interfacial adhesion may be used for the first molding  6  in order to protect the LED  3  and the wires  4 , and silicone having an excellent adhesion with respect to the first molding  6  may be used as the second molding  7  in order to protect the first molding  6  against external impact. 
     The first molding  6  may be formed by dispensing a resin including siloxane and phenyl, and the second molding  7  may be formed by dispensing a resin including siloxane, platinum, and silica to the outside of the first molding  6 . 
     The guide unit  5  may be selectively formed to prevent the resin from flowing down during the forming of the second molding  7  using a dispensing method. 
     The guide unit  5  may be formed of a nonconductive material in a predetermined shape, for example, a shape of a circular ring or a rectangular ring with a predetermined height on the electrode pads  2 . 
     As described above, the LED package according to the present invention includes the LED  3  formed on the planar MCPCB  1  and the first and second moldings  6  and  7  formed in a hemispheric shape outside the LED  3  using a dispensing method. 
     In the present invention, when a material with a high refraction index (RI) is used in the first molding, compared to the second molding, for example, when a material with an RI of 1.51 is used in the first molding and a material with an RI of 1.46 is used in the second molding, the transmittance is improved and thus the light efficiency is improved. This is because the first molding serves as a buffer, improving the transmittance since an RI of air is 1. On the other hands, in a molding structure of the related art, although a material with an RI of 1.51 or 1.46 is used, internal reflection occurs a lot inside the molding, compared to the present invention, and thus the light efficiency decreases by approximately 10%. 
     Therefore, the light efficiency of the LED package may be maximized and a manufacturing method thereof is simple. 
     In particular, the present invention uses materials with an excellent adhesion with respect to each other for the first and second moldings  6  and  7  and thus may prevent a decrease in an adhesion between the first and second moldings  6  and  7  caused by heat generated from the LED  3 . 
     Therefore, a physical stability of the LED is excellent. 
     Hereinafter, a method of forming an LED package according to the present invention will be described. 
       FIG. 3  is a flowchart illustrating a method of forming an LED package according to an embodiment of the present invention. 
     Conductive electrode pads  2  of a predetermined thickness are formed on an MCPCB  1  (S 301 ). The electrode pads  2  are formed by plating a conductive metal material such as Ag, Au, and Cu to a predetermined thickness on the MCPCB  1  using electroplating and etching the metal material such that the electrode pads are spaced from each other by a predetermined distance as illustrated in  FIG. 2 . 
     Next, an LED  3  is mounted on the electrode pads  2 . The LED  3  is connected with the electrode pads  2  through wires  4  (S 302 ). 
     Here, the LED  3  is mounted and connected with the wires  4 , and then a guide unit  5  of a shape of circular ring may be additionally formed around the LED  3  on the electrode pads  2 . 
     A first molding  6  is formed on the LED  3  using a dispensing method (S 303 ). Silicone having a high strength and a good interfacial adhesion may be used for the first molding  6 . 
     Next, a second molding  7  is formed on the first molding  6  (S 304 ). Silicone having an excellent adhesion with respect to the first molding  6  may be used for the second molding  7 . 
     The present invention exemplarily illustrates the SMD type LED package, but is not limited thereto and may be applied to an LED package where an LED is formed in a reflective hole formed in an MCPCB. 
     According to the LED package of the present invention, since the first and second moldings are easily formed using a dispensing method, additional processes are not necessary. Also, adherence between the first and second moldings is improved to increase the physical stability. 
     It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.