Abstract:
The present invention relates to a light emitting diode (LED) package. An object of the present invention is to provide an LED package having a metal PCB, which has a superior heat dissipation property and a compact structure, does not largely restrict use of conventional equipments, and is compatible with an electronic device or illumination device currently used widely. To this end, an LED package according to the present invention comprises a metal printed circuit board (PCB) formed by laminating first and second sheet metal plates with an electric insulating layer interposed therebetween; and an LED chip mounted on the first sheet metal plate of the metal PCB, wherein the first sheet metal plate has electrode patterns and leads respectively extending from the electrode patterns.

Description:
RELATED APPLICATIONS 
   This application claims priority to Korean Patent Application No. 10-2007-0032018, filed Mar. 30, 2007, the contents of which are incorporated herein by reference in their entirety. 
   FIELD OF THE INVENTION 
   The present invention relates to a light emitting diode (LED) package, and more particularly, to an LED package with a metal PCB. 
   BACKGROUND OF THE INVENTION 
   In general, an LED is an element in which electrons and holes are combined in a P-N semiconductor junction structure by application of current thereby emitting certain light. The LED is typically formed to have a package structure, in which an LED chip is mounted, and is frequently referred to as an “LED package.” Such an LED package is generally mounted on a printed circuit board (PCB) and receives current applied from electrodes formed on the PCB to thereby emit light. 
   In an LED package, heat generated from an LED chip has a direct influence on the light emitting performance and life span of the LED package. The reason is that when heat generated from the LED chip remains for a long period of time, dislocation and mismatch occur in a crystal structure of the LED chip. Moreover, a high power LED package has been recently developed. Since the high power LED package is operated by high-voltage power and a large amount of heat is generated in an LED chip due to the high voltage, a separate device for effectively dissipating the generated heat is required. 
   Therefore, there has been developed a conventional LED package for enhancing heat dissipation performance using a metal printed circuit board (metal PCB) in which an insulating layer and a metal pattern layer are sequentially formed on an aluminum base. For example, such a conventional LED package is fabricated in such a manner that a hole cup is formed in the aluminum base so that a portion of the aluminum base is exposed upward by a groove machining process such as cutting, an LED chip adheres to the hole cup, and then the LED chip and the metal pattern layer are connected to each other through a conductive wire. 
   However, the conventional LED package is difficult to be fabricated into a compact structure due to a large thickness of the aluminum base, and does not have a lead structure for electrically connecting the LED chip to external electrodes. For this reason, it may be difficult to mount the conventional LED package on a typically used PCB. This means that the conventional LED package is less compatible with a conventional electronic device or illumination device. Since current LED package manufacturers mostly have equipments suitable for fabricating LED packages with a lead structure, the conventional LED package limits the use of the existent equipments as described above. For this reason, the conventional LED package is also uneconomical. 
   Additionally, in the conventional LED package, since the hole cup is formed by a groove machining process such as a cutting process, the mounting surface of an LED chip is uneven due to the groove machining process, which causes a die attaching process of an LED chip to be difficult. In addition, the die-attached LED chip may be easily damaged due to thermal and mechanical impact. 
   An object of the present invention is to provide an LED package having a metal PCB, which has a superior heat dissipation property and a compact structure, does not largely restrict use of conventional equipments, and is compatible with an electronic device or illumination device currently used widely. 
   An LED package according to an aspect of the present invention comprises a metal printed circuit board (PCB) formed by laminating first and second sheet metal plates with an electric insulating layer interposed therebetween; and an LED chip mounted on the first sheet metal plate of the metal PCB, wherein the first sheet metal plate has electrode patterns and leads respectively extending from the electrode patterns. 
   At this time, each of the leads is preferably formed by bending a portion of the first sheet metal plate extending in an outer side direction from the metal PCB. More preferably, each of the leads has an enlarged contact area with an external electrode through two-step bending of the portion of the first sheet metal plate. Accordingly, each lead can have an enlarged contact area with an external electrode. 
   Alternatively, each of the leads may comprises a terminal pattern formed by patterning the second sheet metal plate in correspondence to the electrode pattern; and a via conductive portion passing through the metal PCB to connect the electrode pattern and the terminal pattern. 
   According to preferred embodiments of the present invention, the first and second sheet metal plates may be made of copper or copper alloy. The LED package may further comprise a molding member formed on the first sheet metal plate to cover the LED chip. The LED package may further comprise a hole cup formed around the LED chip to adjust a directional angle of light emitted from the LED chip. The hole cup may be formed of resin, metal, ceramic or a composite thereof. The hole cup may be made of an FR4 material. Further, the hole cup may include an insulating plate and a metal reflective plate, each of which has an opening, and which are sequentially formed on the first sheet metal plate. In addition, the metal reflective plate may be made of aluminum. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a perspective view showing an LED package according to an embodiment of the present invention; 
       FIG. 2  is a sectional view of the LED package shown in  FIG. 1 ; 
       FIG. 3  is a view illustrating an example of manufacturing a plurality of LED packages having one large metal PCB as a base; and 
       FIG. 4  is a sectional view of an LED package according to another embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
     FIG. 1  is a perspective view showing an LED package according to an embodiment of the present invention, and  FIG. 2  is a sectional view of the LED package shown in  FIG. 1 . 
   As shown in  FIGS. 1 and 2 , the LED package  1  of this embodiment comprises a metal PCB  10 , an LED chip  2  mounted on the metal PCB  10 , and the like. A transparent molding member  31  for protecting the LED chip  2  is formed on the metal PCB  10  in a generally hemispherical shape. The molding member  31  further includes an extension portion  32  extending integrally with the molding member  31  to cover portions of top and side surfaces of the metal PCB  10 , and the extension portion  32  can protect not only the LED chip  2  but also the metal PCB  10  from the outside. 
   The metal PCB  10  of this embodiment comprises first and second sheet metal plates  16  and  12  and an insulating layer  14  interposed between the sheet metal plates  16  and  12 , wherein the first and second sheet metal plates  16  and  12  are laminated with the insulating layer  14  interposed therebetween. The second sheet metal plate  12  is made of copper or copper alloy to form a base of the metal PCB  10 , and the first sheet metal plate  16  is made of copper or copper alloy to be electrically insulated from the second sheet metal plate  12  by the insulating layer  14 . 
   The first sheet metal plate  16  comprises a first electrode pattern  162   a , to which the LED chip  2  adheres, and a second electrode pattern  162   b  patterned to be spaced apart from the first electrode pattern  162   a . The LED chip  2  on the first electrode pattern  162   a  is electrically connected to the second electrode pattern  162   b  by a bonding wire W. At this time, the insulating layer  14  has an electrically insulating property. For the purpose of smooth dissipation of heat generated from the LED chip  2 , the insulating layer  14  is preferably formed of a material with excellent thermal conductivity. 
   According to the embodiment of the present invention, the first sheet metal plate  16  further includes leads  164   a  and  164   b  extending in an outer side direction of the metal PCB  10 . The leads  164   a  and  164   b  are portions connected to external electrodes on an external PCB (not shown) on which the LED package  1  is mounted. Through two-step bending, each of the leads  164   a  and  164   b  is directed downward and has a broad contact area with an external electrode (not shown). That is, each of the leads  164   a  and  164   b  is bent to be directed downward through a first bending process and to fold up through a second bending process, thereby having an end with a thickness greater than the original thickness of the first sheet metal plate  16 . 
   The LED package  1  shown in  FIGS. 1 and 2  is of a top view type in which a package mounting surface and a light emitting surface are positioned to be opposite to each other due to the bending positions and directions of the leads  164   a  and  164   b . However, it may be considered that the bending positions and directions of the leads  164   a  and  164   b  are different from each other whereby the package mounting surface and the light emitting surface are perpendicular to each other. As such, the configuration in which the package mounting surface and the light emitting surface are perpendicular to each other is suitable for implementing an LED package typically called a side view type LED package. 
   In addition, the LED package  1  of this embodiment further includes a hole cup  20  for obtaining a desired directional angle of light, i.e., for adjusting the directional angle of light emitted from the LED chip  2 . The hole cup  20  includes an opening, in which a portion of the molding member  31  is filled, and serves to reflect light within a desired directional angle range by surrounding a circumference of the LED chip  2  on the first sheet metal plate  16 . Since the hole cup  20  is directly laminated on the first sheet metal plate  16  of the metal PCB  10 , it is unnecessary to form the hole cup  20  by machining a groove in the metal PCB  10 . Accordingly, the chip mounting surface of the metal PCB  10  is formed to be flat unlike the prior art. 
   According to the embodiment of the present invention, the hole cup  20  may be used by forming an opening in a plate-shaped member and formed of a resin, metal, ceramic or a composite thereof. As an example, the hole cup  20  may be formed of a material such as FR4. The FR4 is Epoxy Resin Bonded Glass Fiber (ERBGF) reinforced by combining glass fiber with epoxy, which has excellent strength and light reflexibility, and is generally used as a raw material of PCBs. 
   As another example, the hole cup  20  may be formed in such manner that an insulating plate  21  and a metal reflective plate  22 , which are respectively formed with openings, adhere to each other as shown in the enlarged view of  FIG. 2 . At this time, the insulating plate  21  serves to cause the metal reflective plate  22  and the first sheet metal plate  16  positioned under the insulating plate  21  to be electrically insulated. Preferably, the metal reflective plate  22  is made of an aluminum material. 
   According to the embodiment of the present invention, the aforementioned metal PCB  10  is a unit metal PCB cut and separated from a large metal PCB  10 ′ (hereinafter, referred to as a “laminated raw material”) shown in  FIG. 3 , and a plurality of the LED packages  1 , each of which has the metal PCB  10 , are previously formed using the laminated raw material  10 ′ as a base, as shown in  FIG. 3 . The laminated raw material  10 ′ is a laminate of the first sheet metal plate  16 , the insulating layer  14  and the second sheet metal plate  12 , which are patterned and machined to have a predetermined shape. The plurality of LED packages  1  are supported on the laminated raw material  10 ′ through the leads  164   a  and  164   b  extending from the first sheet metal plate  16  and supporting portions  102 ′ of the respective layers. The supporting portions  102 ′ and the leads  164   a  and  164   b  are cut, and the leads  164   a  and  164   b  are bent as described above, thereby completing the unit LED packages  1  each having the configuration shown in  FIGS. 1 and 2 . 
     FIG. 4  is a sectional view of an LED package  1  according to another embodiment of the present invention. The LED package  1  of this embodiment has a configuration substantially equal to the aforementioned embodiment, except the configuration of leads extending from the electrode patterns  162   a  and  162   b  of the first sheet metal plate  16 . Hereinafter, the configuration of the leads different from those of the previous embodiment will be mainly described. 
   As shown in  FIG. 4 , the leads of this embodiment include terminal patterns  121  and  122  formed by patterning a second sheet metal plate  12  in correspondence to electrode patterns  162   a  and  162   b  of a first sheet metal plate  16 , and via conductive portions  165   a  and  165   b  passing through a metal PCB  10  to connect the electrode patterns  162   a  and  162   b  and the terminal patterns  121  and  122 . At this time, the via conductive portions  165   a  and  165   b  may be formed by previously forming openings bored through the metal PCB  10  and then filling the openings with a metal made of the same material as the first sheet metal plate  16  and/or the second sheet metal plate  12 , for example, by a plating method or the like. 
   As described above, an LED package according to the present invention has a sufficient heat dissipation property and a compact structure, and includes leads connected to external electrodes while using a metal PCB and having a structure approximately equal to a general LED package, thereby having excellent compatibility with a conventional electronic device or illumination device. Further, the LED package according to the present invention and a general LED package without a metal PCB are manufactured through a considerably similar process. Thus, there is an economical advantage in that many equipments possessed by current LED package manufacturers can be used in manufacturing the LED package according to the present invention as they are. Furthermore, an additional groove machining process is not required to form a hole cup in which an LED chip is positioned, so that LED package according to the present invention has a flat chip mounting surface. Accordingly, a die attaching process of the LED chip can be performed more easily as compared with a conventional metal PCB-type LED package, and the die attached LED chip is strong against thermal and mechanical impact. 
   Although the present invention have been described with a specified embodiment, it will be apparent to those skilled in the art that various modifications, changes and variations can be made thereto within the scope of the present invention and the appended claims. Therefore, the aforementioned descriptions and the accompanying drawings should be construed as not limiting the technical spirit of the present invention but illustrating the present invention.