Patent Abstract:
A light emission module is provided. The light emission module includes a substrate, a plurality of LED chips disposed on the substrate, a fluorescent colloid and a package colloid surrounding the plurality of LED chips. The substrate includes a substrate body and a plurality of chip pads disposed thereon for carrying the LED chips. A plurality of via holes is formed passing through the chip pads and the substrate body to enhance the heat dissipation of the LED chips. The fluorescent colloid and the package colloid both have light guide structures to improve the color stability and the capacity to process the light shape of the light emission module.

Full Description:
TECHNICAL FIELD 
       [0001]    The present disclosure relates to an LED chip package structure, and particularly relates to a light emission module with high-efficiency light emission and high-efficiency heat dissipation and applications thereof. 
       BACKGROUND 
       [0002]    Light Emitting Diodes (LEDs) are widely used in electronics, most portable backlighting, traffic signals, automotive lighting, and outdoor displays due to the advantages of their long-life span and low power consumption. 
         [0003]    Referring to  FIG. 12  a typical light emission module  10  using LEDs is shown. The light emission module  10  comprises an LED component  11 , a copper foil  12 , an insulated conductor material  14  and an aluminum sheet  16 . The copper foil  12 , the insulated conductor material  14  and the aluminum sheet  16  form a substrate (not labeled) to support the LED component  11  and to dissipate heat generated by the LED component  11 . However, the light emission module of this kind has a complicated manufacturing process and limited heat dissipation efficiency, which results in limited light emission efficiency. 
         [0004]    A known method for packaging LED chips includes: providing a plurality of packaged LEDs that have been packaged by dispensing; and electrically connecting the plurality of packaged LEDs onto a Printed Circuit Board (PCB) one by one to form a light emission module, such as a light bar. However, the light emission module so formed has lower color stability and poor light shape output. 
         [0005]    In addition, current design of circuit layout only allows the LED light bar to be tested as a final product after it is cut off from a mother substrate. This causes lower production efficiency and lower product yield. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The components in the drawing are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the described embodiments. In the drawings, like reference numerals designate corresponding parts throughout various views, and all the views are schematic. 
           [0007]      FIG. 1  is a front view of a light emission module according to a first embodiment of the present disclosure. 
           [0008]      FIG. 2  is a back view of the light emission module of  FIG. 1 . 
           [0009]      FIG. 3  is a perspective view of a part of the light emission module of  FIG. 1 . 
           [0010]      FIG. 4  is another perspective view of a part of the light emission module of  FIG. 1 . 
           [0011]      FIG. 5  is a side view of the light emission module of  FIG. 1 , in which via holes are indicated in dashed lines. 
           [0012]      FIG. 6  is a front view of a light emission module according to a second embodiment of the present disclosure. 
           [0013]      FIG. 7  is a back view of the light emission module of  FIG. 6 . 
           [0014]      FIG. 8  is a front view of a light emission module array, in which electroplated wires are indicated in dashed lines. 
           [0015]      FIG. 9  is a back view of the light emission module array of  FIG. 8 . 
           [0016]      FIG. 10   a  schematically illustrates a structure of a light emission module according to a third embodiment of the present disclosure, in which the light emission module has a light guide structure that may have diffusion or transparent surfaces. 
           [0017]      FIG. 10   b  schematically illustrates a relation between a viewing angle and a luminance of the light emission module of  FIG. 10   a , in which the light guide structure has a diffusion surface. 
           [0018]      FIG. 10   c  schematically illustrates a relation between a viewing angle and a luminance of the light emission module of  FIG. 10   a , in which the light guide structure has a transparent surface. 
           [0019]      FIGS. 11   a - 11   h  schematically illustrate structures of light emission modules according to a fourth to eleventh embodiments of the present disclosure. 
           [0020]      FIG. 12  schematically illustrates the structure of a typical light emission module. 
           [0021]      FIG. 13  is an exploded view of a light emission device according to the present disclosure, the light emission device comprises one of the light emission modules described above. 
           [0022]      FIG. 14  is an exploded view of a display device according to the present disclosure, the display device comprises one of the light emission modules described above. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0023]    Reference will now be made to the drawings to described exemplary embodiments in detail. 
         [0024]      FIGS. 1-5  show different views of a light emission module  100  according to a first embodiment of the present disclosure. The light emission module  100  may comprise a plurality of LED chips  110  and a substrate unit (not labeled). The substrate unit may comprise a substrate body  180 , a chip pad  160 , a plurality of wire pads  170  and a plurality of heat conductors  150 . 
         [0025]    In the following description, the side of the substrate body  180  shown in  FIG. 1  which is facing the reader (i.e. the front side) is referred to as the first side, and the side opposite to the first side (i.e. the rear side) is the second side. A positive electrode trace  182  and a negative electrode trace  186  are respectively formed on the substrate body  180 . 
         [0026]    The chip pad  160  and the wire pads  170  are disposed on the first side of the substrate body  180 . Pluralities of LED chips  110  are arranged on the chip pad  160  by a matrix method, forming a plurality of longitudinal LED chip rows (only one row showed in  FIGS. 1-5 ). Each LED chip  110  has a positive electrode side and a negative electrode side respectively and electrically connected with the positive electrode trace  182  and the negative electrode trace  186  of the substrate unit through respective wire pad  170  and respective wire  112 . The heat conductors  150  are disposed on the second side of the substrate body  180 . A plurality of thermal vias  162  is incorporated into the substrate body  180 , which link the chip pad  160  and respective heat conductor  150  together, to transfer heat generated by the LED chips  110  from the chip pad  160  to the heat conductor  150 . In the illustrated embodiment, no medium is filled in the thermal vias  162 . 
         [0027]    It should be noted that the drawings only schematically shows a thermal via array with 4 rows and 2 columns formed in the substrate body  180  corresponding to each LED chip  110 , and the thermal vias are showed passing through the chip pad  160 , the substrate body  180  and the heat conductor  150 . In practical, the thermal via array may have different number of rows and columns. Moreover, the thermal vias may only pass through the substrate body  180 , but being adjacent to the chip pad  160  and the heat conductor  150 . 
         [0028]    In the illustrated embodiment, the chip pad  160  and the heat conductor  150  may be made of material of high thermal conductivity, and the substrate body  180  may be made of material known to a person skilled in the art. Because of the incorporation of the thermal vias  162 , the heat generated by the LED chips  110  may be transferred from the first side of the substrate body  180  to the second side of the substrate body  180  and then dissipates through the heat conductor  150 . Therefore, the substrate unit and the light emission module  100  as shown have sufficiently high heat dissipation performance. 
         [0029]    Furthermore, at least one gap  188  may be formed at an edge of the substrate body  180 , as shown in  FIG. 1 . The light emission module  100  may be fastened to a light emission device or a display device by a bolt passing through the gap  188  or by snap fit. The configuration may facilitate the heat dissipation from the heat conductor  150  to the light emission device or the display device. Alternatively, at least one position hole may be formed at a place other than the edge of the substrate body as a substitute for the gap. 
         [0030]      FIGS. 6-7  schematically illustrate a light emission module  200  according to a second embodiment of the present disclosure. Similar to the previously described embodiment, the light emission module  200  also comprises a plurality of LED chips  210 , a chip pad  260 , a substrate body  280  and a plurality of thermal vias  262 . The difference lies in that thermal conductivity material (showed in dark region, not labeled) is filled in the thermal vias  262 . The thermal conductivity material may be heat conductive adhesive or heat conductive paste incorporated with metallic component, such as silver paste and copper paste. Thereby, the heat dissipation efficiency of the light emission module  200  is further enhanced due to the filled thermal conductivity material. 
         [0031]      FIGS. 8 and 9  schematically illustrate a light emission module array  300 . In the following description, the side of the light emission module array  300  shown in  FIG. 8  which is facing the reader is referred to as the front side, and the side opposite to the front side is the rear side (as shown in  FIG. 9 ). A plurality of LED chips  310  and a plurality of wire pads  370  are formed on the front side of the light emission module array  300 . A plurality of heat conductors  350  and a plurality of electroplated wires  380  are formed on the rear side of the light emission module array  300 . The heat conductors  350  and the electroplated wires  380  are alternately arranged in the direction L, and each electroplated wire  380  extends in the direction H (L, H labeled in  FIGS. 8 ,  9 , and the electroplated wires  380  are showed in dashed lines in  FIG. 8 ). That is to say, there is an electroplated wire  380  arranged between every two heat conductors  350 . The electroplated wires  380  are electrically connected with corresponding wire pads  370  through respective via holes (not shown) formed in a substrate body of the light emission module array  300 . 
         [0032]    The electroplated wires  380  are of intermediate products, and they function as an electrode to assist a forming of the wire pad  370  during the plating process. Thereby, the electroplated wire  380  becomes useless after the wire pad  370  is formed. However, for the illustrated configuration, the electroplated wire  380  remain exist until the product is finished, thus the testing problem as mentioned in the background may occur. Since each electroplated wire  380  is kept in electrical connection with respective wire pads  370  arranged in direction H, this may cause a short circuit fault between the wire pads  370  and the electroplated wire  380  when tested. Furthermore, solder mask should be disposed upon electroplated wire  380  for insulation purpose. This causes relatively low heat dissipation. 
         [0033]    To overcome the problems mentioned above, a so called “additional etching process” is incorporated herein. The additional etching process is intended to etch the electroplated wires  380  on the light emission module array  300  after the wire pad  370  is formed. This configuration may enable in-line testing during the manufacturing process, and avoid the drawbacks of testing until the product is finished. 
         [0034]      FIG. 10   a  shows a light emission module  400  according to a third embodiment of the present disclosure. The light emission module  400  may comprise a substrate unit  480 , an LED chip  410  disposed on the substrate unit  480 , and a package colloid  420  enclosing the LED chip  410 . The package colloid  420  comprises an integrally formed light guide structure (not labeled). The light guide structure functions as a lens to guide the light emitted from the LED chip  410  and may have multi-shapes and multi-structures which will be described in detail in the following paragraphs. 
         [0035]    The light guide structure of the package colloid  420  may have diffusion or transparent surfaces. The diffusion surfaces may be formed through several methods, for example, by roughing surface of the package colloid  420 , by adding impurity such as Titanium Dioxide or fluorescent powder into the package colloid  420 , or by forming translucent package colloid  420 . The transparent surface may be formed by forming the package colloid  420  into suitable optical lens, for example, a convex lens, a convex-concave lens, or a rod lens. 
         [0036]      FIGS. 10   b  and  10   c  illustrates a relation between a viewing angle and a luminance of the light emission module  400 , in which the light guide structure is of diffusion and transparent surfaces respectively. As seen in  FIG. 10   b , the diffusion surfaces may allow the directive angle to go up to 180°. Therefore, the light emission module of  FIG. 10   b  is suitable for illuminating applications, such as automotive lighting and outdoor displays. In comparison with the diffusion surface, the transparent surface may concentrate the light emitted from the LED chip  410 , and thus narrow the directive angle down to 63°, as shown in  FIG. 10   c . Therefore, the light emission module of  FIG. 10   c  is suitable for backlighting applications, such as liquid crystal display backlighting. 
         [0037]    Referring to  FIGS. 11   a,    11   b,    11   e,    11   g  and  11   h,  each of the light emission modules showed may have fluorescent colloids. The difference lies in that the configuration of the fluorescent colloids varies in terms of quantity and shapes of the light guide structure. Specifically, the fluorescent colloid  520 ′ of  FIG. 11   a  has a light concentrating structure which is transparent; the fluorescent colloid  520  of  FIG. 11   b  has a serrate structure; and the fluorescent colloid  720  of  FIG. 11   e  has a plane surface structure. In  FIG. 11   g,  there is a plurality of fluorescent colloids  920  separately disposed on a substrate body and enclosing respective LED chip  910 . In  FIG. 11   h , there is a single fluorescent colloid  920 ′ disposed on a substrate body and enclosing a plurality of LED chips  910 ′. The fluorescent colloid  920 ,  920 ′ may be formed to enclose the LED chips  910 ,  910 ′ by means of dispensing, spraying or molding. 
         [0038]    Referring to  FIGS. 11   c,    11   d  and  11   f,  each of the light emission modules showed has both a fluorescent colloid and a package colloid. In  FIG. 11   c,  the package colloid  630  is disposed on the fluorescent colloid  620 , and the light guide structure (not labeled) of the fluorescent colloid  620  is arc-shaped. In  FIG. 11   d,  the package colloid  630 ′ is also disposed on the fluorescent colloid  620 ′, however, the light guide structure (not labeled) of the fluorescent colloid  620 ′ is in shape of a plane surface. In  FIG. 11   f,  the fluorescent colloid  820  is disposed on the package colloid  830 , and the light guide structures thereof are both arc-shaped. 
         [0039]    The above-mentioned embodiments of the light emission module may at least have variation as followings. Firstly, a package colloid may be directly disposed on an LED chip and be configured to have similar light guide structures as showed in  FIGS. 11   a ,  11   b  and  11   e . That is to say, the light guide structure of a package colloid may also have diffusion and/or transparent surfaces. The package colloid may be made of light transparent or light translucent material. The package colloid may be formed by means of dispensing, spraying or molding. Secondly, a package colloid may be directly disposed on an LED chip and have similar configurations as showed in  FIGS. 11   g  and  11   h . Furthermore, a combination of the package colloid and the fluorescent colloid may also be configured as showed in  FIGS. 11   g  and  11   h.    
         [0040]    It should be noted that the inventive aspects of the disclosure are described only with reference to the light emission module. In practice, the above-mentioned disclosure may also be applicable to a light emitting element, a light emission device or a display device. For example, the light emission module with the thermal vias  162  may be used to a light emission device such as a lighting tube or a lighting lamp. Moreover, the above-mentioned light emission module may be combined with a display pane to form a display device, such as a liquid crystal display device (LCD) or a variable message sign (VMS). In addition, the above-mentioned substrate body incorporated with the thermal vias may be used in semiconductor and integrated circuits components in order to improve the heat dissipation efficiency. 
         [0041]    Referring to  FIG. 13 , a light emitting device  1000  may comprises an optical sheet  1600 , a plurality of light emission modules  1100 , and a light guide plate (LGP)  1400  disposed therebetween. Each of the light emission modules  1100  may comprise a plurality of LED chips and a substrate unit as mention above (detailed description thereof omitted). The LGP  1400  is adapted to guide light beams provided by the light emission modules  1100  to emit toward the optical sheet  1600 . In particular, the LGP  1400  may comprise a bottom surface (not labeled) and a light emitting surface (not labeled) opposite to the bottom surface. The optical sheet  1600  is configured to convert light beams emitting from the LGP  1400  into uniform planar light, and thereby ensuring the lighting quality. 
         [0042]    Referring to  FIG. 14 , a display device  2000  may comprises an optical sheet  2600 , a plurality of light emission modules  2100 , an LGP  2400  disposed therebetween, and a display panel  2800 . Each of the light emission modules  2100  may comprise a plurality of LED chips and a substrate unit as mention above (detailed description thereof omitted). The LGP  2400  is adapted to guide light beams provided by the light emission modules  2100  to emit toward the optical sheet  2600 . The optical sheet  2600  is configured to convert light beams emitting from the LGP  2400  into uniform planar light, and thereby ensuring the display quality of the display panel  2800 , so as to enable the display panel  2800  to display images. 
         [0043]    It is to be understood, however, that even though numerous characteristics and advantages of preferred and exemplary embodiments have been set out in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only; and that changes may be made in detail within the principles of present disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.

Technology Classification (CPC): 5