Patent Publication Number: US-2012025258-A1

Title: Light emitting diode package and light emitting diode module

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates generally to light emitting devices, and more particularly to a light emitting diode (LED) package and an LED module having the LED package. 
     2. Description of Related Art 
     LEDs are solid state light emitting devices formed of semiconductors, which are more stable and reliable than other conventional light sources such as incandescent bulbs. Thus, LEDs are being widely used in various fields such as numeral/character displaying elements, signal lights, light sources for lighting and display devices. When in use, providing LEDs in packages can provide protection, color selection, focusing and the like for light emitted by the LEDs. 
     A typical LED package includes a base with an LED chip encapsulated thereon. The LED package is generally formed as a surface mounting type device for facilitating application, whereby the base is mounted on a printed circuit board or other similar elements. Solder paste such as tin is used between the base and the printed circuit board for soldering the LED package on the printed circuit board. However, the existent of solder paste easily results in floating or inclination of the LED package. When heating the solder paste to bond the LED package onto the printed circuit board, the solder paste is prone to spill over the base of the LED package. The above mentioned factors not only interfere the soldering of the LED package, but also destroy aesthetics of the LED package. In addition, the solder paste is also prone to generate voids therein due to heating flux thereof, which increases a heat resistance of the solder paste and negatively affects the heat dissipation of the LED package. 
     What is needed therefore is an LED package and an LED module having the LED package which can overcome the above mentioned limitations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the views. 
         FIG. 1  is a side view of an LED package in accordance with a first embodiment of the present disclosure. 
         FIG. 2  is a cross sectional view of an LED package in accordance with a second embodiment of the present disclosure. 
         FIG. 3  is a cross sectional view of an LED package in accordance with a third embodiment of the present disclosure. 
         FIG. 4  is a cross sectional view of an LED package in accordance with a forth embodiment of the present disclosure. 
         FIG. 5  is a top view of an LED package in accordance with a fifth embodiment of the present disclosure. 
         FIG. 6  is a cross sectional view of the LED package shown in  FIG. 5 , taken along line VI-VI thereof. 
         FIG. 7  is a top view of an LED package in accordance with a sixth embodiment of the present disclosure. 
         FIG. 8  is a cross sectional view of the LED package shown in  FIG. 7 , taken along line VIII-VIII thereof. 
         FIG. 9  is a cross sectional view of an LED package in accordance with a seventh embodiment of the present disclosure. 
         FIGS. 10 and 11  are bottom views of bases of LED packages in different embodiments of the present disclosure. 
         FIG. 12  is a cross sectional view of an LED module in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  illustrates an LED package  10  in accordance with an embodiment of the present disclosure. The LED package  10  includes a base  20 , an LED chip  30  mounted on a surface of the base  20 , two electrodes  40  formed on the base  20  and electrically connected to the LED chip  30 , and an encapsulant  50  encapsulating the LED chip  30 . At least one groove  22  is defined in a surface of the base  20  opposite the LED chip  30 . 
     The base  20  may be plastic, ceramics, or other insulating materials. The base  20  may be rectangular, round or polygonal in shape. The LED chip  30  is mounted on a first surface such as a top surface of the base  20 . 
     The LED chip  30  is connected to the electrodes  40  with metal wires  42  by wire bonding. It is understood that the LED chip  30  may also be connected to the electrodes  40  by flip chip technique in an alternative embodiment. 
     In the present embodiment, the at least one groove  22  is configured to be plural. The grooves  22  are straight, parallel to each other and defined in a second surface such as a bottom surface of the base  20 . A cross section of each groove  22  can be rectangular, arc, polygonal or other suitable geometric configurations. The grooves  22  defined in the bottom surface of the base  20  increase a surface area of the base  20  and are capable of receiving more solder paste therein, which is benefit for avoiding inclination of the LED package  10  or spill of the solder paste when bonding the LED package  10  to a printed circuit board or other similar elements. Further, the grooves  22  may function as vents for air generated by the solder paste when heated, whereby voids defined by the air in the solder paste can be prevented. Specifically, in this embodiment, the grooves  22  extend to an edge of the base  20  and communicate with an outside of the base  20  for obtaining a better function of air evacuation. A depth of the grooves  22  is generally ⅕-½ of a thickness of the base  20 . The base  20  having the grooves  22  with such a depth provides an acceptable strength and meanwhile an acceptable receiving space for the solder paste. Metal may be plated on the bottom surface of the base  20  defining all or a portion of the grooves  22 , for easily adhering the solder paste to the base  20 . 
     The encapsulant  50  is transparent or translucent, and may be made of resins, glass or other suitable materials. The encapsulant  50  can be configured as spherical, elliptical, or rectangular. 
     Referring to  FIG. 2 , an LED package  11  in accordance with an embodiment of the present disclosure further includes a plurality of electrically conductive holes  24  and heat conductive holes  25  defined in the base  20 . The electrically conductive holes  24  and heat conductive holes  25  extend from the top surface through the bottom surface of the base  20 . Electrically conductive materials  241  and heat conductive materials  251  such as metal are respectively received in the electrically conductive holes  24  and heat conductive holes  25 . The electrically conductive materials  241  are connected to the electrodes  40 . The heat conductive materials  251  have a higher heat conductivity than the base  20  and connect to a metal layer  43  mounted on the base  20 . Heat generated by the LED chip  30  can be transferred by the metal layer  43  and the heat conductive materials  251 . Specially, a heat conductive hole  25  corresponding to the position of the LED chip  30  is larger than other heat conductive holes  25 , which is an advantage for heat dissipation of the LED chip  30 . The electrically conductive holes  24  and heat conductive holes  25  may be round, rectangular, square in a top view. The cross sections of the electrically conductive holes  24  and heat conductive holes  25  may be rectangular, trapeziform or other shapes. 
     The grooves  22  are defined in the base  20  by machining the base  20  in the previous embodiments. It is understood that the grooves  22  can also be defined by other fashions. Referring to  FIG. 3 , the base  20  in a third embodiment comprises a plurality of plate-shaped electrically conductive materials  241  and heat conductive materials  251  (such as metal), and a plurality of plate-shaped, electrically isolating materials  201  (such as ceramics, plastic, etc.) presented in an alternating fashion. The electrically conductive materials  241  and heat conductive materials  251 , and the isolating materials  201  are vertically placed. The electrically conductive materials  241  and heat conductive materials  251  are higher than the isolating materials  201 . Tops of the electrically conductive materials  241 , heat conductive materials  251  and insolating materials  201  are flushed with each other, whereby grooves  22  are defined between bottoms of neighboring electrically conductive materials  241 , heat conductive materials  251  and isolating materials  201 . 
     An LED package  12  in accordance with a forth embodiment of the present disclosure is illustrated in  FIG. 4 . The LED package  12  further comprises a reflection cup  21  formed on the top surface of the base  20 . The LED chip  30  is positioned at a bottom of the reflection cup  21 . The encapsulant  50  is received in the reflection cup  21 . The reflection cup  21  and the base  20  can be formed integrally in an alternative embodiment. An angle defined between the top surface of the base  20  and a reflecting surface (i.e., an inner surface) of the reflection cup  21  can be 90-130 degrees. 
     Referring to  FIGS. 5 and 6 , the LED chip  30  of an LED package  13  in accordance with a fifth embodiment of the present disclosure is a vertical type LED chip. A bottom of the LED chip  30  is directly connected to an electrode  40  to accomplish an electrical connection. A top of the LED chip  30  is electrically connected to another electrode  40  via a metal wire  42 . A plurality of electrically conductive holes  24  and heat conductive holes  25  are defined in the base  20 , and electrically conductive materials and heat conductive materials are respectively received in the electrically conductive holes  24  and heat conductive holes  25 . Specially, a density of the heat conductive holes  25  around the LED chip  30  is higher than that at other positions. Thus, heat generated by the LED chip  30  can be dissipated more efficiently. 
     Referring to  FIGS. 7 and 8 , the LED chip  30  of an LED package  14  in accordance with a sixth embodiment of the present disclosure is mounted on the base  20  by a flip chip technique. The LED chip  30  connects the electrodes  40  for obtaining electrical power. One of the heat conductive holes  25  in the base  20  has a square shape in a top view, and a cross section of the heat conductive hole  25  is trapeziform. 
     An LED package  15  in accordance with a seventh embodiment of the present disclosure shown in  FIG. 9  comprises a substantially columned base  20 , an LED chip  30  mounted on a top surface of the base  20 , two electrodes  40  formed on the base  20  and electrically connected to the LED chip  30 , and an encapsulant  50  encapsulating the LED chip  30 . A plurality of grooves  22  are defined in a bottom surface of the base  20 . The base  20  is made of a material with high heat conductivity, and heat generated by the LED chip  30  can be dissipated by the base  20 . A phosphor layer  32  covers the LED chip  30 . The phosphor layer  32  may contain YAG phosphors, silicon oxynitride phosphors, nitride phosphors, etc. The LED package  15  further comprises a substrate  60  surrounding the base  20 . The electrodes  40  extend out from the substrate  60  and are flush with the bottom surface of the base  20 . 
     A plurality of grooves  22  with different fashions defined in the base  20  are shown in  FIGS. 10 and 11 . The grooves  22  may present as curved or net configuration. The grooves  22  extend to an edge of the base  20  and communicate with the outside of the base  20 . 
     Referring to  FIG. 12 , an LED module in accordance with an embodiment of the present disclosure includes a board  70  such as a printed circuit board, and an LED package mounted on the board  70 . The LED package is identical to the LED package  15  shown in  FIG. 9 . The bottom surface of the base  20 , in which the grooves  22  are defined, is attached to the board  70 . It is noted that the LED package can be any LED package shown in the previous embodiments. It is further noted that in one embodiment, the grooves  22  can be formed by different fashions shown in such as the first and third embodiments. The LED package is secured on the board  70  by the solder paste  71 . The grooves  22  positioned at the bottom surface of the base  20  can serve as a container for receiving excessive solder paste  71 , preventing the excessive solder paste from spilling over the base  20 . Floating and inclination of the LED package due to the excessive solder paste can also be avoided. The electrodes  40  are electrically connected to the board  70  by soldering, for example, surface mounting technology (SMT). 
     It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the disclosure.