Patent Publication Number: US-2009224266-A1

Title: LED chip package structure applied to a backlight module and method for making the same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of The Invention 
     The present invention relates to an LED chip package structure and a method for making the same, and particularly relates to an LED chip package structure applied to a backlight module and a method for making the same. 
     2. Description of the Related Art 
     Referring to  FIG. 1 , a known method for packaging LED chips is shown. The known method includes: providing a plurality of packaged LEDs that have been packaged (S 800 ); providing an elongated substrate body that has a positive trace and a negative trace (S 802 ); and then, arranging each packaged LED on the elongated substrate body in sequence and electrically connecting a positive side and a negative side of each packaged LED with the positive trace and the negative trace of the substrate body (S 804 ). 
     However, with regard to the known method, each packaged LED needs to be firstly cut from an entire LED package structure, and then each packaged LED is arranged on the elongated substrate body via SMT process. Hence, the known packaging process is time-consuming. Moreover, because the fluorescent bodies are separated from each other, a dark band is easily produced between the two fluorescent bodies and the two LEDs. Hence, the known LED package structure does not offer a good display for users. Moreover, because the package bodies of the packaged LEDs are separated from each other, a dark band is easily produced between two adjacent package bodies and the two packaged LEDs. Hence, the known LED package structure does not offer a good display for users. 
     SUMMARY OF THE INVENTION 
     The present invention provides an LED chip package structure applied to a backlight module and a method for making the same. When the LED chip package structure of the present invention lights up, the LED chip package structure generates a series of light-generating areas on a body unit. Because the series of light-generating areas is continuous, no dark bands are produced between two adjacent LED chips. Furthermore, because the LED chips are arranged on a substrate body via a COB (Chip On Board) method and a hot pressing method, the process for the LED chip package structure is simple and less time is needed for the manufacturing process. Furthermore, the LED chip package structure can be applied to any type of light source such as a back light module, a decorative lamp, a lighting lamp, or a scanner. 
     A first aspect of the present invention is an LED chip package structure applied to a backlight module, including: a substrate unit, a light-emitting unit, a package body unit and an opaque unit. The light-emitting unit has a plurality of LED chips electrically arranged on the substrate unit. The package body unit has a plurality of package bodies respectively covering the LED chips. The opaque unit has a plurality of opaque frame bodies formed on the substrate unit, and two opaque frame bodies are respectively formed on two lateral sides of each package body. 
     A second aspect of the present invention is a method for making an LED chip package structure applied to a backlight module, including: providing a substrate unit; electrically arranging a plurality of LED chips on the substrate unit via a matrix method to form a plurality of longitudinal LED chip rows; and longitudinally and respectively covering the longitudinal LED chip rows with a plurality of elongated package bodies. 
     The method further includes: forming a plurality of elongated opaque frame bodies on the substrate unit, wherein the two elongated opaque frame bodies are respectively formed on two lateral sides of each elongated package body; and transversely cutting the elongated package bodies, the elongated opaque frame bodies and the substrate unit along lines each between adjacent and longitudinal LED chips to form a plurality of light bars, wherein each light bar has a plurality of package bodies that are separated from each other and respectively covering the LED chips and a plurality of opaque frame bodies that are separated from each other and respectively formed on two lateral sides of each package body. 
     Therefore, because the series of light-generating areas are continuous, no dark bands are produced between two adjacent LED chips. Furthermore, because the LED chips are arranged on the substrate body via a COB (Chip On Board) method and a hot pressing method, the process of the present invention is simple and so reduces the required manufacturing time. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed. Other advantages and features of the invention will be apparent from the following description, drawings and claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawings, in which: 
         FIG. 1  is a flowchart of a method for packaging LED chips of the prior art; 
         FIG. 2  is a flowchart of a method of packaging LED chips package structure according to the first embodiment of the present invention; 
         FIGS. 2   a  to  2   e  are perspective, schematic diagrams of a packaging process according to the first embodiment of the present invention, respectively; 
         FIGS. 2A to 2E  are cross-sectional diagrams of a packaging process according to the first embodiment of the present invention, respectively; 
         FIG. 3  is a schematic view of LED chips electrically connected on a substrate body via a flip-chip method; 
         FIG. 4A  is a lateral, schematic view of an LED chip package structure applied to a backlight module according to the first embodiment of the present invention; 
         FIG. 4B  is a cross-sectional view of line B-B in  FIG. 4A ; 
         FIG. 5  is a flowchart of a method of packaging LED chips package structure according to the second embodiment of the present invention; 
         FIGS. 5   a  to  5   b  are partial, perspective, schematic diagrams of a packaging process according to the second embodiment of the present invention, respectively; and 
         FIGS. 5A to 5B  are partial, cross-sectional diagrams of a packaging process according to the second embodiment of the present invention, respectively. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED BEST MOLDS 
     Referring to  FIGS. 2 ,  2   a  to  2   e,  and  2 A to  2 E, the first embodiment of the present invention provides a method for making an LED chip package structure applied to a backlight module. The method includes: referring to  FIGS. 2   a  and  2 A, providing a substrate unit  1 , the substrate unit having a substrate body  10 , and a positive trace  11  and a negative trace  12  respectively formed on the substrate body  10  (S 100 ). 
     Moreover, the substrate body  10  has a metal layer  10 A and a Bakelite layer  10 B formed on the metal layer  10 A. The substrate unit  1  can be a PCB (Printed Circuit Board), a flexible substrate, an aluminum substrate, a ceramic substrate, or a copper substrate according to different needs. In addition, both the positive trace  11  and the negative trace  12  can be aluminum circuits or silver circuits. The layouts of the positive trace  11  and the negative trace  12  are determined by different needs. 
     Referring to  FIGS. 2   b  and  2 B, the method of the first embodiment further includes: arranging a plurality of LED chips  20  on the substrate body  10  via a matrix method to form a plurality of longitudinal LED chip rows  2 , each LED chip  20  having a positive side  201  and a negative side  202  respectively and electrically connected with the positive trace  11  and the negative trace  12  of the substrate unit  1  (S 102 ). 
     In the first embodiment, the positive side  201  and the negative side  202  of each LED chip  20  are respectively and electrically connected with the positive trace  1  and the negative trace  12  of the substrate unit  1  via two corresponding leading wires W via a wire-bounding method. Moreover, each longitudinal LED chip row  2  is straightly arranged on the substrate body  10  of the substrate unit  1 . Each LED chip  20  can be a blue LED chip or an LED chip set for generating white light such as an LED chip set composed of a red LED, a green LED and a blue LED. 
     However, the above-mentioned method of electrically connecting the LED chips  20  should not be used to limit the present invention. For example, referring to  FIG. 3 , the positive side  201 ′ and the negative side  202 ′ of each LED chip  20 ′ respectively and electrically connected with the positive trace  11 ′ and the negative trace  12 ′ of the substrate unit  1 ′ via a plurality of corresponding solder balls B via a flip-chip method. Moreover, according to different needs, positive sides and negative sides of LED chips (not shown) can be electrically connected to a positive trace and a negative trace of a substrate unit (not shown) via parallel, serial, or parallel and serial method. 
     Referring to  FIGS. 2   c  and  2 C, the method of the first embodiment further includes: longitudinally and respectively covering the longitudinal LED chip rows  2  with a plurality of elongated fluorescent bodies  3  (S 104 ). Moreover, the present invention can use a plurality of elongated transparent bodies to replace the elongated fluorescent bodies. If the present invention uses the elongated fluorescent bodies, the LED chips are blue LED chips. If the present invention uses the elongated transparent bodies, the LED chips is an LED chip set for generating white light such as an LED chip set composed of a red LED, a green LED and a blue LED. 
     Furthermore, the first mold unit M 1  is composed of a first upper mold M 11  and a first lower mold M 12  for supporting the substrate body  10 . The first upper mold M 11  has a plurality of first channels M 110  corresponding to the longitudinal LED chip rows  2 . 
     The height and the width of each first channel M 110  are the same as the height and the width of each elongated fluorescent body  3 . Moreover, each elongated fluorescent body is a fluorescent resin that is formed by mixing silicon and fluorescent powders or mixing epoxy and fluorescent powders according to different needs. 
     Finally, referring to  FIGS. 2   d  and  2 D, the method of the first embodiment further includes: forming a plurality of elongated opaque frame bodies  4  on the substrate body  10  via a second mold unit M 2 , and the two elongated opaque frame bodies  4  respectively formed on two lateral sides of each elongated fluorescent body  3  (S 106 ). Moreover, the second mold unit M 2  is composed of a second upper mold M 21  and a second lower mold M 22  for supporting the substrate body  10 . The second upper mold M 21  has a plurality of second channels M 210  corresponding to the elongated opaque frame bodies  4 , and the height of each second channel M 210  is the same as the height of each elongated fluorescent body  3 . 
     Finally, referring to  FIGS. 2   d,    2   e,  and  2 E, the method of the second embodiment further includes: transversely cutting the elongated fluorescent bodies  3 , the elongated opaque frame bodies  4  and the substrate body  10  along lines each between adjacent and longitudinal LED chips  20  to form a plurality of light bars L 1 , and each light bar L 1  having a plurality of fluorescent bodies  30  that are separated from each other and respectively covering the LED chips  20  and a plurality of opaque frame bodies  40  that are separated from each other and respectively formed on two lateral sides of each fluorescent body  30  (S 108 ). Moreover, the longitudinal width of each fluorescent body  30  and each opaque frame body  40  is below 0.3 mm, such as between 0.01 mm and 0.3 mm. 
     Referring to  FIGS. 4A and 4B , the first embodiment of the present invention further includes: respectively and longitudinally disposing two reflective boards  5  beside the two sides of the substrate body  10 , and disposing a light-guiding board  6  over the LED chips  20  (S 110 ). Hence, light beams S generated by the LED chips  20  are guided along a predetermined direction by mating the two reflective boards  5  and the opaque frame bodies  40 . In addition, the light-guiding board  6  is used to receive the light beams S that have been guided by mating the two reflective boards  5  and the opaque frame bodies  40 . 
     Referring to  FIGS. 5 ,  5   a  to  5   b,  and  5 A to  5 B, steps S 200  to S 204  of the second embodiment are same as steps S 100  to S 104  of the first embodiment. In other words, the illustration of S 200  is the same as  FIGS. 2   a  and  2 A of the first embodiment, the illustration of S 202  is the same as  FIGS. 2   b  and  2 B of the first embodiment, and the illustration of S 204  is the same as  FIGS. 2   c  and  2 C of the first embodiment. 
     After step of S 204 , referring to  FIGS. 5 ,  5   a  and  5 A, the method of the second embodiment further includes: forming a plurality of elongated opaque frame bodies  4 ′ on the substrate body  10  via a second mold unit M 2 ′, and each elongated opaque frame body  4 ′ formed between the two elongated fluorescent bodies  3  (S 206 ). Two of the elongated opaque frame bodies  4 ′ are respectively formed on the left side of the left-most elongated fluorescent body  3  and the right side of the right-most elongated fluorescent body  3 . Moreover, the second mold unit M 2 ′ is composed of a second upper mold M 21 ′ and a second lower mold M 22 ′ for supporting the substrate body  10 . The second upper mold M 21 ′ has a plurality of second channels M 210 ′ corresponding to the elongated opaque frame bodies  4 ′. 
     Finally, referring to  FIGS. 5 ,  5   b,  and  5 B, the method of the second embodiment further includes: transversely cutting the elongated fluorescent bodies  3 , the elongated opaque frame bodies  4 ′ and the substrate body  10  along lines each between adjacent and longitudinal LED chips  20  to form a plurality of light bars L 2 , and each light bar L 2  having a plurality of fluorescent bodies  30  that are separated from each other and respectively covering the LED chips  20  and a plurality of opaque frame bodies  40 ′ that are separated from each other, and each opaque frame body  40 ′ is formed between the two fluorescent bodies  30  (S 208 ). 
     In conclusion, when the LED chip package structure of the present invention lights up, the LED chip package structure generates a series of light-generating areas on a body unit. Because the series of light-generating areas is continuous, no dark bands are produced between two adjacent LED chips. Furthermore, because the LED chips are arranged on a substrate body via a COB (Chip On Board) method and a hot pressing method, the process of the LED chip package structure is simple and therefore reduces the required manufacturing time. Furthermore, the LED chip package structure can be applied to any type of light source such as a back light module, a decorative lamp, a lighting lamp, or a scanner. 
     Although the present invention has been described with reference to the preferred best molds thereof, it will be understood that the invention is not limited to the details thereof. Various substitutions and modifications have been suggested in the foregoing description, and others will occur to those of ordinary skill in the art. Therefore, all such substitutions and modifications are intended to be embraced within the scope of the invention as defined in the appended claims.