Patent Publication Number: US-RE48617-E

Title: Package of light emitting diode and method for manufacturing the same

Description:
CROSS-REFERENCE FOR RELATED APPLICATIONS 
     This application is a Continuation of co-pending U.S. patent application Ser. No. 12/162,105 filed on Jul. 24, 2008, which is the national phase of PCT International Application No. PCT/KR2007/000381 filed on Jan. 23, 2007, and which claims priority to Application No. 10-2006-0008158 filed in the Republic of Korea on Jan. 26, 2006. The entire content of all of the above applications is hereby incorporated by reference.This application is a reissue application of U.S. application Ser. No. 13/052,587, filed Mar. 21, 2011 and issued as U.S. Pat. No. 8,217,413 on Jul. 10, 2012, which is a continuation of U.S. patent application Ser. No. 12/162,105 filed on Jul. 24, 2008 and issued as U.S. Pat. No. 7,935,976 on May 3, 2011, which is the national phase of PCT International Application No. PCT/KR2007/000381 filed on Jan. 23, 2007, and which claims priority to Application No. 10-2006-0008158 filed in the Republic of Korea on Jan. 26, 2006. The entire content of all of the above applications is hereby incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a package of a light emitting diode, and a method for manufacturing the same. 
     BACKGROUND ART 
     An example of a related art light-emitting diode (LED) module is formed as illustrated in  FIG. 1 . As for the related art LED module of  FIG. 1 , each of LED chips corresponding to a red LED  2 , a green LED  3  and a blue LED  4  respectively is mounted in one independent package. The package is molded with lens-shaped epoxy to form an individual device as a module. 
     An example of a related art LED packaging method includes a method of flip-bonding a light-emitting diode chip on a submount of a silicon optical bench (SIOB), or a method of using a metal core printed circuit board (MCPCB). 
     The MCPCB refers to a chip on board (COB) structure where an LED chip is directly die-bonded to a printed circuit board (PCB), and then wire bonding is performed thereon for electrical connection. 
     However, in the case where the MCPCB is used among COB type packages according to the related art, an insulating layer is provided on the thick MCPCB. Here, since a lower metal of the MCPCB is flexible while having a thick thickness, deformation may occur when the MCPCB is pressed, a defective rate thus increases, and inconvenience is caused in handling the MCPCB during a process operation. 
     Also, the thick thickness of the lower metal of the MCPCB according to the related art undesirably obstructs formation of a slim package 
     Furthermore, since the LED chip does not directly contact a metal plate according to the related art, heat generated from the LED chip cannot be sufficiently released. 
     DISCLOSURE OF INVENTION 
     Technical Problem 
     The present invention provides an LED package and a method for manufacturing the same, which can satisfy demands for a slim package by providing a surface mounting type LED package capable of solving disadvantages, such as a thick MCPCB, of the related art LED package. 
     Technical Solution 
     In one embodiment of the present invention, there is provided a package of a light emitting diode including: a metal plate; a light-emitting diode chip surface-mounted on the metal plate; an insulating layer on the metal plate, the insulating layer separated from the light-emitting diode chip; a lead frame on the insulating layer; a reflective coating layer on the lead frame; and a molding material molding the light-emitting diode chip in a predetermined shape. 
     In another embodiment of the present invention, there is provided a method for manufacturing a package of a light-emitting diode, including: forming an insulating layer under a lead frame; forming a light-emitting diode mounting region in the lead frame and the insulating layer; forming a metal plate under the insulating layer in which the light-emitting diode mounting region is formed; forming a reflective coating layer on the lead frame; surface-mounting a light-emitting diode chip on the metal plate in the mounting region; and performing molding on the light-emitting diode chip. 
     In another embodiment, there is provided a package of a light emitting diode, the package comprising: a base layer; a light emitting diode chip on the base layer; a lead frame electrically connected to the light emitting diode chip; a reflective coating layer directly on the lead frame; and a molding material covering the light emitting diode chip in a predetermined shape, wherein a bottom surface of the reflective coating layer is positioned higher than a bottom surface of the light emitting diode chip, wherein the lead frame includes at least one end portion that is not covered with the reflective coating layer, the at least one portion of the lead frame being adjacent to the light emitting diode chip, and wherein a bottom surface of the reflective coating layer is substantially parallel to a top surface of the base layer. 
     In another embodiment, there is provided a display device: comprising a package of a light emitting diode, the package including a base layer; a light emitting diode chip on the base layer; a lead frame electrically connected to the light emitting diode chip; a reflective coating layer directly on the lead frame; and a molding material covering the light emitting diode chip in a predetermined shape, wherein a bottom surface of the reflective coating layer is positioned higher than a bottom surface of the light emitting diode chip, wherein the lead frame includes at least one end portion that is not covered with the reflective coating layer, the at least one portion of the lead frame being adjacent to the light emitting diode chip, and wherein a bottom surface of the reflective coating layer is substantially parallel to a top surface of the base layer. 
     Advantageous Effects 
     An LED package and a method for manufacturing the same according to the present invention can meet demands for a slim package by using a thin metal plate and thus considerably reducing a thickness of a PCB. 
     Also, according to the present invention, since an LED chip is mounted on the metal plate, heat generated from the LED chip is directly conducted to the metal plate, and thus effective heat release can be achieved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exemplary view of a related art LED package; and 
         FIGS. 2 through 5  are cross-sectional views of a method for manufacturing an LED package according to an embodiment of the present invention. 
     
    
    
     MODE FOR THE INVENTION 
     An LED package and a method for manufacturing the same according to an embodiment of the present invention will now be described in detail with reference accompanying drawings. 
     It will be understood that when a layer (or film) is referred to as being ‘on’ or ‘under’ another layer or substrate, it can be directly on or under the other layer or substrate, or intervening layers may also be present. 
       FIGS. 2 through 5  are cross-sectional views of a method for manufacturing an LED package according to an embodiment of the present invention. 
     Referring to  FIG. 2 , an insulating layer  32  is attached to a lead frame  33 . 
     The lead frame  33  is formed of a copper alloy, and may include a circuit with a predetermined pattern. 
     Also, the insulating layer  32  may be formed of a glass epoxy-based material, for example, a flame retardant-4 (FR-4) resin  32 . Here, the FR-4 resin  32  is an insulator made of a dielectric resin, and has a high mechanical strength and excellent durability, thereby experiencing just small thermal deformation even if the FR-4 resin  32  has a thin thickness. Also, the FR-4 resin  32  is a proper material for formation of multiple layers because of its adhesiveness. 
     When the FR-4 resin  32  is attached to a surface of the lead frame  33  using a press or a thermo-compression jig, the FR-4 resin  32  is attached thereto by heat applied by the press or the thermo-compression jig because of the adhesiveness of the FR-4 resin  32 . 
     Referring to  FIG. 3 , an LED mounting region is formed in the lead frame  33  and the FR-4 resin  32 . 
     Specifically, the FR-4 resin  32  and the lead frame  33  that are attached together are punched by a mechanical method, for example, a drilling machine, to for iii a space where an LED chip  35  of  FIG. 5  is to be mounted. 
     Here, an attached plate of the FR-4 resin  32  and the lead frame  33  may be punched to form an LED mounting space having a cylindrical shape or a quadrangle-shaped container. 
     Instead, a punched section of the FR-4 resin  32  and the lead frame  33  may be an inclined surface that is tapered from the lead frame  33  toward the FR-4 resin  32   
     Then, referring to  FIG. 3 , a metal plate  31  is high-temperature compressed and attached to a lower surface of the FR-4 resin  32 . 
     Here, the metal plate  31  may be formed of a metal material having thermal conductivity, such as aluminum (Al) and silver (Au). 
     Since the metal plate  31  is thinner than that of the related art, the metal plate  31  contributes to considerably reducing the thickness of the PCB to meet demands for a slim package. 
     For example, the metal plate  31  has a thickness ranging from about 25 D to about 75 D, and acts as a heat sink. Also, as the LED chip  35  of  FIG. 5  is mounted on the metal plate  31 , so that the demands for the slimness of the LED package can be satisfied. 
     Also, when the metal plate  31  is high-temperature compressed and attached to the lower surface of the FR-4 resin  32 , the press or the thermo-compression jig may be used in the same manner as when the FR-4 resin  32  and the lead frame  33  are attached together. 
     Then, referring to  FIG. 4 , a reflective coating layer  34  is formed on an upper surface of the lead frame  33 . 
     Here, the reflective coating layer  34  may be formed of a material with high reflectance in order to improve brightness of light emitted from the LED chip  35 . 
     The reflective coating layer  34  may include a white resin including titanium oxide and resin as main components and formed by mixing calcium carbonate, barium sulfate, zinc oxide, or the like. 
     Also, the reflective coating layer  34  may be formed using a white pigment besides the white resin. 
     In the present invention, a screen printing method, not a related art pneumatic dispensing method which has been widely used, is proposed as a method for applying the white resin for the reflective coating layer  34 . 
     As compared to the related art pneumatic dispensing method, the screen printing method can apply the white resin to a relatively large area within a short period of time, and requires a small equipment investment cost. 
     A screen mask (not shown) having a thickness of, for example, 50 D, is formed on a punched portion of the FR-4 resin  32  and the lead frame  33 , specifically, on a space in which the LED chip  35  is to be mounted. Thereafter, a portion excluding the screen mask is filled with the white resin using a squeeze (not shown). 
     Specifically, the squeeze moves along an upper surface of the screen mask while rubbing a liquid white resin in a preset direction, so that the portion excluding the screen mask can be filled with the liquid white resin. 
     After the portion excluding the screen mask is filled with the liquid white resin, the screen mask is removed, and annealing is performed at a preset temperature to cure the white resin, and a surface of the white resin is planarized on the same level as the upper surface of the screen mask. 
     Then, referring to  FIG. 5 , the LED chip  35  is mounted on the metal plate  31  in the mounting space. 
     The LED chip  35  is mounted on the metal plate  31  using paste (not shown) having thermal conductivity, and the LED chip  35  and the lead frame  33  can be electrically connected using a wire  36 . 
     Also, in the present invention, the LED chip may be flip-bonded to a silicon optical bench (SIOB) (not shown), the SIOB to which the LED chip flip-bonded has been flip-bonded may be mounted on the metal plate  31 , and electrical connection therebetween may be made using a wire. 
     After the LED chip  35  is mounted, an epoxy resin, as a molding material  37 , is injected for molding to a space encompassed by the FR-4 resin  32 , the lead frame  33  and the reflective coating layer  34  over the LED chip  35 . 
     A surface mounting type LED package formed in the above-described manner can meet the demands for a slim package since a thin metal layer having a thickness ranging from about 25 D to 75 D is used, and thus a thin thickness of about 0.6 mm to about 0.4 mm is implemented between the reflective coating layer  34  and the metal plate  31 . 
     Also, according to the present invention, since the LED chip is mounted on the metal plate, heat generated from the LED chip can be directly conducted to the metal plate, thereby achieving effective heat-release. 
     INDUSTRIAL APPLICABILITY 
     It will be apparent to those skilled in the art that various modifications and variations can he 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. 
     Specifically, although one LED chip is taken as an example for describing a surface mounting type LED package according to the present invention, the present invention is not limited thereto, and a plurality of packages each including a plurality of LED chips can be implemented and used for a backlight unit of a liquid crystal display (LCD) device.