Patent Publication Number: US-2010127294-A1

Title: Side view type light-emitting diode package structure, and manufacturing method and application thereof

Description:
RELATED APPLICATIONS 
     This application claims priority to Taiwan Application Serial Number 97145554, filed Nov. 25, 2008, which is herein incorporated by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to a light-emitting diode (LED) package structure, and more particularly to a side view type light-emitting diode package structure and its applications in a light-emitting diode light bar and a light-emitting diode backlight module. 
     BACKGROUND OF THE INVENTION 
     With the trend towards energy conservation and environmental protection, light-emitting diodes have become the most conspicuous energy saving light sources in light sources replacing the currently existing light sources. Among the light-emitting diode light sources, surface mounting type (SMT) light-emitting diodes are widely applied. The typical light-emitting diode chips generally cannot transform majority of the input electric energy into light energy, and the electric energy is mostly lost in the form of thermal energy, so that the transformation efficiency of the light-emitting diode chips is poor. If the heat produced during the operation of the light-emitting diode chip cannot be effectively eliminated, the junction temperature of the light-emitting diode chip is greatly increased, thereby reducing the luminous efficiency of the light-emitting diode chip and decreasing the reliability of the light-emitting diode chip. Therefore, how to resolve the heat-dissipating problem has become an important subject of the development of the light-emitting diode device. 
     Typically, high-power light-emitting diodes are referred to 1 W or more than 1 W light-emitting diodes. A larger current is needed to input into a high-power light-emitting diode chip, so that the heat-dissipating problem is more important. Refer to  FIG. 1 .  FIG. 1  illustrates a cross-sectional view of a conventional high-power SMT light-emitting diode package structure. A light-emitting diode package structure  100  mainly includes a light-emitting diode chip  104 , a package base  102 , a lead frame  106 , a wire  108  and a package encapsulant  110 . The package base  102  is formed of polyphthalamide (PPA) by an injection-molding method. Typically, the lead frame  106  is combined with the package base  102  during the injection-molding of the package base  102 . The lead frame  106  further includes a heat sink  114  in addition to two electrically separated leads  112 . The heat sink  114  is combined with one of the leads  112 , and the heat sink  114  is much thicker than the leads  112  to improve the heat-dissipating ability. The package base  102  includes a cavity  116 , wherein a bottom of the cavity  116  exposes one lead  112  of the lead frame  106  and a portion of the heat sink  114 . 
     The light-emitting diode chip  104  is disposed in the cavity  116  of the package base  102  and is located on the exposed portion of the heat sink  114  of the lead frame  106 , so that the heat produced by the light-emitting diode chip  104  can be rapidly conducted via the heat sink  114 . In addition, two electrodes of the light-emitting diode chip  104  are electrically connected to the two leads  112  of the lead frame  106  by, for example, using the wire  108  or a flip-chip method. The package encapsulant  110  is filled into the cavity  116  of the package base  102  and covers the light-emitting diode chip  104  and the wire  108 . 
     The heat sink  114  can enhance the heat-dissipating effect of the light-emitting diode package structure  100 , so that the light-emitting diode package structure  100  can be applied in a high-power light-emitting diode device of more than 1 W. However, the conventional high-power light-emitting diode package structure  100  still has the following disadvantages. The light-emitting diode package structure  100  is a top view type light-emitting diode package structure and has a larger size, so that the light-emitting diode package structure  100  cannot be applied in a backlight module with a thin light guide plate. In addition, the difference between the thermal conduction coefficients of the material of the package base  102  and the semiconductor material of the light-emitting diode chip  104  is large, so that the connection of the package base  102  and the light-emitting diode chip  104  is easily broken by the thermal expansion, thereby reducing the reliability of the light-emitting diode package structure  100 . Furthermore, the surface of the package base  102  usually needs cleaning in the process and the polyphthalamide surface of the package base  102  is easily damaged after the package base  102  is cleaned by plasma, so that thereby decreasing the reflectivity of the surface of the package base  102  and thereby affecting the intensity of the emitted of light. Moreover, with the design of the heat sink  114 , the thickness of the lead frame  106  and the heat sink  114  is irregular and the difference of the thickness is large, so that the process of manufacturing the lead frame  106  together with the heat sink  114  is complicated, and a scrap issue is caused, thereby being adverse for reducing the cost. 
     SUMMARY OF THE INVENTION 
     Therefore, one aspect of the present invention is to provide a side view type light-emitting diode package structure and a method for manufacturing the same, which uses silicon as the material of a package base. The thermal expansion coefficient of silicon is closer to that of semiconductor material of a light-emitting diode chip, so that it can prevent the connection of the light-emitting diode chip and the silicon package base from being affected by the thermal expansion to increase the reliability of the side view type light-emitting diode package structure. 
     Another aspect of the present invention is to provide a side view type light-emitting diode package structure and a method for manufacturing the same, in which a silicon package base has a superior heat-conducting ability, so that a conventional lead frame, which includes a metal heat sink and has a highly irregular thickness, is not needed, thereby greatly reducing the difficulty of manufacturing the lead frame and solving the scrap issue that occurs in the process of manufacturing the lead frame. 
     Still another aspect of the present invention is to provide a side view type light-emitting diode package structure and its applications in a light-emitting diode light bar and a light-emitting diode backlight module, in which a package base has a superior heat-conducting property, so that the package structure is suitable for a low-power light-emitting diode chip and a high-power light-emitting diode chip of more than 1 W. 
     Further another aspect of the present invention is to provide a side view type light-emitting diode package structure and its applications in a light-emitting diode light bar and a light-emitting diode backlight module, in which a surface of a cavity of a silicon package base formed by using a semiconductor process is smooth, so that the surface of the cavity can be used as a reflective surface directly, the reflective effect of the reflective surface is not affected by the plasma cleaning, and the package base has a better reflective effect than the conventional plastic base. 
     Still further another aspect of the present invention is to provide a side view type light-emitting diode package structure and its applications in a light-emitting diode light bar and a light-emitting diode backlight module. The light-emitting diode package structure is the side view type, so that the width of the light-emitting diode light bar and the thickness of the side-edged type backlight module can be effectively reduced. 
     According to the aforementioned aspects, the present invention provides a side view type light-emitting diode package structure. The side view type light-emitting diode package structure includes a silicon base, a first conductive lead, a second conductive lead and a first light-emitting diode chip. The silicon base includes a first cavity, and the first cavity defines a light-extracting surface of the side view type light-emitting diode package structure. The first conductive lead is disposed at least on a portion of the first cavity and extends to an outer surface of the silicon base. The second conductive lead is disposed at least on another portion of the first cavity and extends to the outer surface of the silicon base, wherein the first conductive lead and the second conductive lead are electrically isolated from each other. The first light-emitting diode chip includes a first electrode and a second electrode, and the first electrode and the second electrode are electrically connected to the first conductive lead and the second conductive lead respectively, wherein the outer surface of the silicon base is substantially perpendicular to the light-extracting surface. 
     According to a preferred embodiment of the present invention, the silicon base is a one-piece structure. 
     According to the aforementioned aspects, the present invention provides a method for manufacturing a side view type light-emitting diode package structure including the following steps. A silicon base is provided, wherein the silicon base includes a first cavity and a second cavity respectively set in a first surface and a second surface of the silicon base adjacent to each other, and the first cavity defines a light-extracting surface of the side view type light-emitting diode package structure. At least two conductive leads are formed to cover the first cavity and to extend on the second cavity, wherein the conductive leads are electrically isolated from each other, and the light-extracting surface is substantially perpendicular to the portions of the conductive leads located in the second cavity. At least one light-emitting diode chip is disposed in the first cavity, wherein the light-emitting diode chip includes two electrodes electrically connected to the conductive leads respectively. A package encapsulant is formed to cover the light-emitting diode chip. 
     According to a preferred embodiment of the present invention, the method further includes forming an insulation layer to at least cover a bottom surface of the first cavity between the step of providing the silicon base and the step of forming the conductive leads. 
     According to another aspect, the present invention provides a method for manufacturing a side view type light-emitting diode package structure including the following steps. A silicon sub-base is provided, wherein the silicon sub-base includes a first surface and a second surface adjacent to each other, and the silicon sub-base includes a first cavity located in the second surface. At least two conductive leads are formed to cover and to extend on the first surface of the silicon sub-base and a surface of the first cavity, wherein the conductive leads are electrically isolated from each other. A silicon cavity portion is disposed on the first surface of the silicon sub-base, wherein the silicon sub-base and the silicon cavity portion define a second cavity, and the second cavity exposes a portion of each conductive lead. The second cavity defines a light-extracting surface of the side view type light-emitting diode package structure, and the light-extracting surface is substantially perpendicular to the portions of the conductive leads located in the first cavity. At least one light-emitting diode chip is disposed in the second cavity, wherein the light-emitting diode chip includes two electrodes electrically connected to the conductive leads respectively. A package encapsulant is formed to cover the light-emitting diode chip. 
     According to a preferred embodiment of the present invention, the step of disposing the silicon cavity portion further includes using an adhesion layer to connect the silicon cavity portion and the silicon sub-base. 
     According to still another aspect, the present invention provides a light-emitting diode light bar and its application in a light-emitting diode backlight module. The light-emitting diode backlight module includes a carrier, a light guide plate and at least one light-emitting diode light bar. The light guide plate is disposed on the carrier. The light-emitting diode light bar is disposed beside a light-entering surface of the light guide plate. The light-emitting diode light bar includes a circuit board and at least one side view type light-emitting diode package structure. The side view type light-emitting diode package structure includes a silicon base, a first conductive lead, a second conductive lead and a first light-emitting diode chip. The silicon base includes a first cavity, and the first cavity defines a light-extracting surface of the side view type light-emitting diode package structure. The first conductive lead is disposed at least on a portion of the first cavity and extends to an outer surface of the silicon base. The second conductive lead is disposed at least on another portion of the cavity and extends to the outer surface of the silicon base, wherein the first conductive lead and the second conductive lead are electrically isolated from each other. The first conductive lead and the second conductive lead are located on a plane surface of the circuit board, and the light-extracting surface is substantially perpendicular to the plane surface of the circuit board. The first light-emitting diode chip includes a first electrode and a second electrode, and the first electrode and the second electrode are electrically connected to the first conductive lead and the second conductive lead respectively. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention are more readily appreciated as the same become better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  illustrates a cross-sectional view of a conventional high-power SMT light-emitting diode package structure; 
         FIG. 2  is a three-dimensional drawing of a side view type light-emitting diode package structure in accordance with a preferred embodiment of the present invention; 
         FIG. 3  illustrates a cross-sectional view of the side view type light-emitting diode package structure taken along a cross-sectional line A-A′ of  FIG. 2 ; 
         FIG. 4A  through  FIG. 4G  are schematic flow diagrams showing a process of manufacturing a side view type light-emitting diode package structure in accordance with a preferred embodiment of the present invention; 
         FIG. 5  is a three-dimensional drawing of a side view type light-emitting diode package structure in accordance with another preferred embodiment of the present invention; 
         FIG. 6  illustrates a cross-sectional view of the side view type light-emitting diode package structure taken along a cross-sectional line B-B′ of  FIG. 5 ; 
         FIG. 7A  through  FIG. 7F  are schematic flow diagrams showing a process of manufacturing a side view type light-emitting diode package structure in accordance with another preferred embodiment of the present invention; 
         FIG. 8  is a schematic diagram showing a light-emitting diode backlight module in accordance with a preferred embodiment of the present invention; and 
         FIG. 9  is a schematic diagram showing a light-emitting diode backlight module in accordance with another preferred embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Refer to  FIG. 2  and  FIG. 3 .  FIG. 2  and  FIG. 3  respectively illustrate a three-dimensional drawing of a side view type light-emitting diode package structure in accordance with a preferred embodiment of the present invention and a cross-sectional view of the side view type light-emitting diode package structure taken along a cross-sectional line A-A′ of  FIG. 2 . A side view type light-emitting diode package structure  200  mainly includes a silicon base  202 , two conductive leads  218 , one or more light-emitting diode chips  212  and a package encapsulant  228 . In the present exemplary embodiment, the silicon base  202  is a one-piece structure. In one embodiment, the silicon base  202  includes adjacent surfaces  204  and  206 . The silicon base  202  includes a first cavity  208 , and the first cavity  208  is set in the surface  204  of the silicon base  202 , wherein the first cavity  208  defines a light-extracting surface  224  of the side view type light-emitting diode package structure  200 . In the present exemplary embodiment, the silicon base  202  further includes a second cavity  210 , wherein the second cavity  210  is set in the surface  206  of the silicon base  202 . Such as shown in  FIG. 2  and  FIG. 3 , the conductive leads  218  both cover the first cavity  208  in the surface  204  of the silicon base  202  and both extend to cover the second cavity  210  in the surface  206 , wherein the conductive leads  218  are electrically isolated from each other. Each conductive lead  218  may be a single-layered structure made of a single material layer, or may be a multi-layered structure formed by stacking at least two material layers. Such as shown in  FIG. 3 , in the present exemplary embodiment, each conductive lead  218  includes a seed layer  214  and an electroplating layer  216  stacked on the silicon base  202  in sequence, so that each conductive lead  218  is a multi-layered structure. The material of the seed layer  214  may be Cu, Au, Ag or Ni, for example. The material of the electroplating layer  216  may be Cu, Ag or Ni, for example. 
     As shown in  FIG. 3 , the light-emitting diode chip  212  is disposed in the first cavity  208  of the silicon base  202 , and the light-emitting diode chip  212  may be disposed on the conductive lead  218 , for example. In one embodiment, in order to provide better insulation between the silicon base  202  and the light-emitting diode chip  212 , an insulation layer (not shown) may be selectively formed on the silicon base  202  to dispose the insulation layer between the conductive leads  218  and the silicon base  202 . The material of the insulation layer may be silicon dioxide, silicon nitride or ceramics, for example. The light-extracting surface  224  of the side view type light-emitting diode package structure  200  is substantially perpendicular to the surface  206  on an outer side of the silicon base  202 . In the present exemplary embodiment, the side view type light-emitting diode package structure  200  has one single light-emitting diode chip  212 . In other exemplary embodiments, the side view type light-emitting diode package structure  200  may include a plurality of light-emitting diode chips  212 . Each light-emitting diode chip  212  includes two electrodes  222 , wherein the electrodes  222  have different conductivity types. For example, one of the electrodes  222  is P-type, and the other of the electrodes  222  N-type. In the present exemplary embodiment, the light-emitting diode chip  212  has a horizontal electrode structure, i.e. the two electrodes  222  of the light-emitting diode chip  212  are located on the same side of the light-emitting diode chip  212 . In accordance with the design of multiple light-emitting diode chips  212 , the side view type light-emitting diode package structure  200  may include more than two conductive leads, such as several conductive leads  218 . In one embodiment, all electrodes  222  respectively correspond to the conductive leads  218 , and the electrodes  222  may be electrically connected to the corresponding conductive leads  218  via wires  226  respectively. In another embodiment, a common cathode or common anode design may be adopted, so that the side view type light-emitting diode package structure  200  has more electrodes  222  than conductive leads  218 , and each one of a part of conductive leads  218  is electrically connected to at least two of the electrodes  222  via the wires  226 . The light-emitting diode chips  212  may have the same color tone, for example, all light-emitting diode chips  212  may be blue. The light-emitting diode chips  212  may also have different color tones, for example, the light-emitting diode chips  212  may include two green light-emitting diode chips, one red light-emitting diode chip and one blue light-emitting diode chip. 
     In one exemplary embodiment, according to the brightness requirement of the product, the side view type light-emitting diode package structure  200  may selectively include a reflective layer  220  covering a side surface of the first cavity  208  of the silicon base  202 , such as shown in  FIG. 3 . The reflective layer  220  may be a metal reflective layer, a nonmetal reflective layer or a metal layer/nonmetal layer compound structure, for example. In one embodiment, the side surface of the first cavity  208  may be directly used as a reflective surface without setting a reflective layer. The package encapsulant  228  is filled in the first cavity  208  of the silicon base  202  and covers the light-emitting diode chip  212 , and preferably covers the wire  226  simultaneously. In one exemplary embodiment, the package encapsulant  228  may be mixed with fluorescent powder. The choice of the fluorescent powder may be made according to the desired color of the light of the device and the color of the light emitted by the light-emitting diode chip  212 . In one embodiment, when the desired color of the light of the device is white, and the light-emitting diode chip  212  emits blue light, the package encapsulant  228  may be mixed with yellow fluorescent powder, or red-green fluorescent powder. 
     Refer to  FIG. 4A  through  FIG. 4G .  FIG. 4A  through  FIG. 4G  are schematic flow diagrams showing a manufacturing process for a side view type light-emitting diode package structure in accordance with a preferred embodiment of the present invention. In one exemplary embodiment, in the manufacture of the side view type light-emitting diode package stricture  200 , a silicon substrate  232  is provided, such as shown in  FIG. 4A . Next, such as shown in  FIG. 4B , first and second cavities  208  and  210  are defined in the silicon substrate  232  by, for example, a photolithography and etching technique. The silicon substrate  232  may be defined by, for example, a wet etching process to form the first cavity  208  in the surface  204  of each silicon base  202 . The wet etching process may use KOH or HF as the etchant. In another embodiment, a reactive ion etching (RIE) process may be used to form the first cavity  208  in the surface  204  of the silicon base  202 . One or more second cavities  210  may be formed in the silicon substrate  232  by, for example, a reactive ion etching process to define a plurality of silicon bases  202 . The second cavity  210  is located in the surface  206  of the silicon base  202 , and the second cavity  210  has a width w. The thickness of the conductive lead  218  (referring to  FIG. 4C ) formed sequentially may be controlled by controlling the width w of the second cavity  210 . 
     In order to provide a better insulation property between the light-emitting diode chip  212  (referring to  FIG. 4D ) sequentially disposed and the silicon base  202 , an insulation layer (not shown) may be selectively formed on a bottom of the first cavity  208  of the silicon base  202  or on the entire outer surface of the silicon base  202 . In the formation of the insulation layer, silicon dioxide or silicon nitride may be formed by, for example, a deposition method or a furnace thermal oxidation method, or a ceramic layer may be formed by, for example, a deposition method. A better heat-conducting effect can be provided by using the ceramic layer as the insulation layer. 
     Referring to  FIG. 4C , at least two conductive leads  218  are formed to cover the first cavity  208  in the surface  204  of the silicon base  202 , and to extend and cover the second cavity  210  in another surface  206 . The conductive leads  218  are electrically isolated from each other. In one embodiment, each conductive lead  218  may be a single-layered structure. In one exemplary embodiment, each conductive lead  218  may be a multi-layered structure. For example, a thin seed layer  214  is firstly formed to cover the silicon base  202  by a pattern defining technique, a sputtering or evaporation deposition method in the semiconductor process. The seed layer  214  includes two or more portions defined by a semiconductor pattern defining technique, and the portions are electrically isolated from each other. Then, an electroplating layer  216  is formed on the seed layer  214  by using the seed layer  214  as the base and using, for example, an electroplating method, to complete the conductive leads  218  electrically isolated from each other. The thickness of the seed layer  214  may be adjusted according to the process and may be controlled between about hundreds of Å and about thousands of Å. The material of the seed layer  214  may be, for example, Cu, Au, Ag or Ni. The thickness of the electroplating layer  216  may be controlled by using the width w of the second cavity  210  defined in the silicon base  202 , and is preferably slightly less than the width w to benefit the sequential cutting and dividing process of the package base. The material of the electroplating layer  216  may be, for example, Cu, Ag or Ni. In the present exemplary embodiment, the conductive leads  218  are formed by an electroplating method to prevent the material stress issue caused by bending the metal material many times in the prior art. 
     Then, simultaneously referring to  FIG. 4D  and  FIG. 2 , one or more light-emitting diode chips  212  are disposed in the first cavity  208  of each silicon base  202 . Each light-emitting diode chip  212  includes two electrodes  222  of different conductivity types, such as shown in  FIG. 2 . Then, the electrodes  222  are electrically connected to the corresponding conductive leads  218  by a flip-chip method or a wire bonding method with the use of the wires  226  shown in  FIG. 2 , for example. Each conductive lead  218  is electrically connected to one or more electrodes  222  correspondingly. 
     Next, such as shown in  FIG. 4E , the reflective layer  220  may be selectively formed to cover the side surface of the first cavity  208  of the silicon base  202  according to the brightness requirement of the product. In one embodiment, the side surface of the first cavity  208  can be directly used as the reflective surface without forming a reflective layer. Then, such as shown in  FIG. 4F , the package encapsulant  228  is formed to fill in the first cavity  208  of the silicon base  202  and to cover the light-emitting diode chip  212  and the wire  226 . In one embodiment, the package encapsulant  228  may be mixed with fluorescent powder, such as yellow fluorescent powder or red-green fluorescent powder. In the present exemplary embodiment, the light-extracting surface  224  of the side view type light-emitting diode package structure  200  is substantially perpendicular to the portion of the conductive lead  218  extending to the surface  206  on the outer side of the silicon based  202 . 
     Then, referring to  FIG. 4G , the silicon material connected between two adjacent silicon bases  202  is separated by, for example a backside etching process, to separate the side view type light-emitting diode package structures  200 , so as to form the structure shown in  FIG. 2  and  FIG. 3 . In another embodiment, the structure shown in  FIG. 2  and  FIG. 3  can be obtained through separating the side view type light-emitting diode package structures  200  by a split process. 
     Refer to  FIG. 5  and  FIG. 6 .  FIG. 5  and  FIG. 6  respectively illustrate a three-dimensional drawing of a side view type light-emitting diode package structure in accordance with another preferred embodiment of the present invention, and a cross-sectional view of the side view type light-emitting diode package structure taken along a cross-sectional line B-B′ of  FIG. 5 . A side view type light-emitting diode package structure  200   a  mainly includes a silicon base  202   a,  two conductive leads  218   a,  one or more light-emitting diode chips  212   a  and a package encapsulant  228 . In the present exemplary embodiment, the silicon base  202   a  is not a one-piece structure, and is formed by stacking a silicon sub-base  234  and a silicon cavity portion  236 . The silicon sub-base  234  is connected to a bottom surface of the silicon cavity portion  236 . In one embodiment, an adhesion layer (not shown) may be used to connect the silicon sub-base  234  and the silicon cavity portion  236 . The material of the adhesion layer may be polymer or adhesion glue, such as epoxy. In one embodiment, the silicon base  202   a  includes surfaces  204  and  206  adjacent to each other. The silicon base  202   a  includes a first cavity  208 , and the first cavity  208  is set in the surface  204  of the silicon base  202   a.  In the present exemplary embodiment, such as shown in  FIG. 6 , the silicon base  202   a  further includes a second cavity  210 , wherein the second cavity  210  is set in the surface  206  of the silicon base  202   a.  In the present exemplary embodiment, the first cavity  208  is defined by the silicon sub-base  234  and the silicon cavity portion  236  cooperatively, and the first cavity  208  defines a light-extracting surface  224  of the side view type light-emitting diode package structure  202   a.  In one embodiment, the light-extracting surface  224  of the side view type light-emitting diode package structure  202   a  is substantially perpendicular to the surface  206  on the outer side of the silicon base  202   a.  Such as shown in  FIG. 5  and  FIG. 6 , the first cavity  208  of the silicon base  202   a  exposes the conductive leads  218   a  and the conductive leads  218   a  extend to cover the second cavity  210  in the surface  206 , wherein the conductive leads  218   a  are electrically isolated from each other. Each conductive lead  218   a  may be a single-layered structure made of a single material layer, or may be a multi-layered structure formed by stacking at least two material layers. Such as shown in  FIG. 6 , in the present exemplary embodiment, each conductive lead  218   a  includes a seed layer  214   a  and an electroplating layer  216   a  stacked on the silicon base  202   a  in sequence, so that each conductive lead  218   a  is a multi-layered structure. The material of the seed layer  214   a  may be Cu, Au, Ag or Ni, for example. The material of the electroplating layer  216   a  may be Cu, Ag or Ni, for example. 
     Such as shown in  FIG. 6 , in one embodiment, in order to provide better insulation between the silicon base  202   a  and the light-emitting diode chip  212   a,  an insulation layer  238  may be selectively formed on the silicon sub-base  234  of the silicon base  202   a,  wherein the insulation layer  238  is located between the silicon sub-base  234  and the silicon cavity portion  236  and under the conductive leads  218   a.  In another embodiment, the insulation layer  238  may be located between the entire conductive leads  218   a  and the silicon sub-base  234  to provide a further better insulation effect. The material of the insulation layer  238  may be silicon dioxide, silicon nitride or ceramics, for example. In the present exemplary embodiment, the conductive leads  218   a  outwardly extends from the silicon sub-base  234  to an outer surface of the silicon base  202   a  directly, and the conductive leads  218   a  are not like the conductive leads  218  which outwardly extend from the side wall of the first cavity  208 . Therefore, a portion of the insulation layer  238  and a portion of each conductive lead  218   a  are located in between the silicon cavity portion  236  and the silicon sub-base  234  of the silicon base  202   a.  With such design of the conductive lead  218   a,  the reflective surface in the first cavity  208  of the silicon base  202   a  is not affected by the conductive lead  218   a  to prevent an undesired reflective path of the light-emitting diode chip  212   a  from being formed so as to prevent the luminous efficiency from being reduced. 
     Such as shown in  FIG. 6 , the light-emitting diode chip  212   a  is disposed in the first cavity  208  of the silicon base  202   a,  and the light-emitting diode chip  212   a  may be disposed on the conductive lead  218   a,  for example. In the present exemplary embodiment, the side view type light-emitting diode package structure  200   a  has two light-emitting diode chips  212   a.  In other exemplary embodiments, the side view type light-emitting diode package structure  200   a  may include one single or more than two light-emitting diode chips  212   a.  Each light-emitting diode chip  212   a  includes two electrodes  222   a,  wherein the electrodes  222   a  have different conductivity types. For example, one of the electrodes  222   a  is P-type, and the other of the electrodes  222   a  N-type. In the present embodiment, the light-emitting diode chip  212   a  has a vertical electrode structure, i.e. the two electrodes  222   a  of the light-emitting diode chip  212   a  are respectively located on two opposite sides of the substrate of the light-emitting diode chip  212   a.  In order to match the design of multiple light-emitting diode chips  212   a,  the side view type light-emitting diode package structure  200   a  may include more than two conductive leads, such as three conductive leads  218   a.  In one embodiment, all electrodes  222   a  respectively correspond to the conductive leads  218   a,  and the electrodes  222   a  may be electrically connected to the corresponding conductive leads through the wires  226 . Such as shown in  FIG. 5 , in one exemplary embodiment, a common cathode or common anode design may be adopted, so that the amount of the whole electrodes  222   a  of the side view type light-emitting diode package structure  200   a  is larger than that of the conductive leads  218   a,  and the conductive leads  218   a  are electrically connected to the two electrodes  222   a  respectively in the two light-emitting diode chips  212   a  via two wires  226 . The light-emitting diode chips  212   a  may be light-emitting diode chips of the same color tone, for example, all light-emitting diode chips  212   a  may be blue light-emitting diode chips. The light-emitting diode chips  212   a  may include light-emitting diode chips of different color tones, for example, the light-emitting diode chips  212   a  may include two green light-emitting diode chips, one red light-emitting diode chip and one blue light-emitting diode chip. 
     In one exemplary embodiment, such as shown in  FIG. 6 , according to the brightness requirement of the product, the side view type light-emitting diode package structure  200   a  may selectively include a reflective layer  220  covering a side surface of the first cavity  208  of the silicon base  202   a.  The reflective layer  220  may be a metal reflective layer, a nonmetal reflective layer or a metal layer/nonmetal layer compound structure. Similarly, the side surface of the first cavity  208  may be directly used as a reflective surface without setting a reflective layer. The package encapsulant  228  is filled in the first cavity  208  of the silicon base  202   a  and covers the light-emitting diode chips  212   a  and the wires  226 . In one exemplary embodiment, the package encapsulant  228  may be mixed with fluorescent powder. The choice of the fluorescent powder may be made according to the desired color of the light of the device and the color of the light emitted by the light-emitting diode chip  212   a.  In one embodiment, when the desired color of the light of the device is white, and the light-emitting diode chip  212   a  emits blue light, the package encapsulant  228  may be mixed with yellow fluorescent powder, or red-green fluorescent powder. 
     Refer to  FIG. 7A  through  FIG. 7F .  FIG. 7A  through  FIG. 7F  are schematic flow diagrams showing a process of manufacturing a side view type light-emitting diode package structure in accordance with another preferred embodiment of the present invention. In one exemplary embodiment, in the manufacture of the side view type light-emitting diode package structure  200   a,  a silicon substrate  240  is provided. Next, such as shown in  FIG. 7A , in order to provide better insulation between the silicon base  202   a  and the light-emitting diode chip  212   a  (referring to  FIG. 7E ), an insulation layer  238  may be selectively formed to cover a surface of the silicon substrate  240 . Silicon dioxide or silicon nitride may be formed by, for example, a deposition method or a furnace thermal oxidation method to be used as the insulation layer  238 , or a ceramic layer may be formed by, for example, a deposition method to be used as the insulation layer  238 . A better heat-conducting effect can be provided by using the ceramic layer as the insulation layer. The thickness of the insulation layer  238  is preferably larger than that of the conductive lead  218   a.    
     Next, such as shown in  FIG. 7B , disposition regions  242  and the desired thickness of the conductive leads  218   a  (referring to  FIG. 7C ) to be formed are defined on the insulation layer  238  by, for example, a photolithography and etching method. Then, one or more second cavities  210  are defined in the silicon substrate  240  by, for example, a photolithography and etching method to define the disposition regions  242  of the conductive leads  218   a  and a plurality of silicon sub-bases  234 . When the silicon substrate  240  is etched, a dry etching process, such as a reactive ion etching process, may be used. Each silicon sub-base  234  includes surfaces  244  and  246  adjacent to each other, wherein the insulation layer  238  is located on the surface  244  of the silicon sub-base  234 . A portion of the second cavity  210  is located in the surface  246  of the silicon sub-base  234 , and the second cavity  210  has a width w. The thickness of the conductive lead  218   a  formed sequentially may be controlled by controlling the width w of the second cavity  210 . In the embodiment without insulation layer  238 , the silicon substrate  240  is directly defined to form one or more second cavities  210  by, for example, a photolithography and etching method, so as to form the disposition regions  242  of the conductive leads  218   a  and a plurality of silicon sub-bases  234 . 
     Next, referring to  FIG. 7C , at least two conductive leads  218   a  are formed to cover the disposition regions  242  in the insulation layer  238  and to extend and cover the second cavity  210  in the surface  246  of the silicon sub-base  234 . The conductive leads  218   a  are electrically isolated from each other. In one embodiment, each conductive lead  218   a  may be a single-layered structure. In one exemplary embodiment, each conductive lead  218   a  may be a multi-layered structure. For example, a thin seed layer  214   a  is firstly formed to cover the insulation layer  238  on the surface  244  of the silicon sub-base  234  and the surface of the second cavity  210  of the silicon sub-base  234  by a pattern defining technique and a sputtering or evaporation deposition method in the semiconductor process. The seed layer  214   a  includes two or more portions defined by a semiconductor pattern defining technique, and the portions are electrically isolated from each other. Then, an electroplating layer  216   a  is formed on the seed layer  214   a  by using the seed layer  214   a  as the base and using, for example, an electroplating method, to complete the conductive leads  218   a  electrically isolated from each other. The thickness of the seed layer  214   a  may be adjusted according to the process and may be controlled between about hundreds of Å and about thousands of Å. The material of the seed layer  214   a  may be, for example, Cu, Au, Ag or Ni. The thickness of the electroplating layer  216   a  may be controlled by using the width w of the second cavity  210  defined in the silicon sub-base  234 , and is preferably slightly less than the width w to benefit the sequential cutting and dividing process of the package base. The material of the electroplating layer  216   a  may be, for example, Cu, Ag or Ni. In the present exemplary embodiment, the conductive leads  218   a  are formed by an electroplating method to prevent the material stress issue caused by bending the metal material many times in the prior art. In some embodiments, the conductive leads  218   a  with the desired thickness may be directly grown by, for example, a sputtering or evaporation method, and the electroplating process is not needed. 
     Then, such as shown in  FIG. 7D , a silicon cavity portion  236  is disposed on the surface  244  of the silicon sub-base  234 , and the surface  244  of the silicon sub-base  234  is bonded to the bottom surface of the silicon cavity portion  236  to form the silicon base  202   a.  In one embodiment, an adhesion layer (not shown) may be selectively used to connect the silicon cavity portion  236  and the silicon sub-base  234 . The material of the adhesion layer may be polymer or adhesion glue, such as epoxy. Referring to  FIG. 5  and  FIG. 7D  simultaneously, in the silicon base  202   a,  the silicon sub-base  234  and the silicon cavity portion  236  define the first cavity  208 . The first cavity  208  exposes a portion of each conductive lead  218   a.    
     Then, referring to  FIG. 5  and  FIG. 7E  simultaneously, one or more light-emitting diode chips  212   a  are disposed in the first cavity  208  of each silicon base  202   a.  Each light-emitting diode chip  212   a  includes two electrodes  222   a  of different conductivity types, and the electrodes  222   a  are respectively disposed on two opposite sides of the light-emitting diode chip  212   a.  Next, the electrodes  222   a  are electrically connected to the corresponding conductive leads  218   a  by a flip-chip method or a wire bonding method with the use of the wires  226  shown in  FIG. 5 , for example. As the above description in accordance with  FIG. 5 , each conductive lead  218   a  is electrically connected to one or more electrodes  222   a  correspondingly. Next, according to the brightness requirement of the product, the reflective layer  220  may be selectively formed to cover the side surface of the first cavity  208  of the silicon base  202   a,  or the side surface of the first cavity  208  can be directly used as the reflective surface without forming a reflective layer. Then, the package encapsulant  228  is formed to fill in the first cavity  208  of the silicon base  202   a  and to cover the light-emitting diode chips  212   a  and the wires  226 . In one embodiment, the package encapsulant  228  may be mixed with fluorescent powder, such as yellow fluorescent powder or red and green fluorescent powder. Sequentially, such as shown in  FIG. 7F , a portion of the silicon cavity portion  236  and a portion of the silicon sub-base  234  are removed respectively from the top of the silicon cavity portion  236  and the bottom of the silicon sub-base  234  by using the conductive lead  218   a  as the etching stop layer and using, for example, a dry etching method to separate the side view type light-emitting diode package structures  200   a,  so as to form the structure shown in  FIG. 5  and  FIG. 6 . In the present exemplary embodiment, the light-extracting surface  224  of the side view type light-emitting diode package stricture  200   a  is substantially perpendicular to the portion of the conductive lead  218   a  extending to the surface  206  on the outer side of the silicon based  202   a.    
     According to the aforementioned exemplary embodiments, the side view type light-emitting diode package structure includes the following advantages. The expansion coefficient of silicon base is closer to that of the semiconductor material of the light-emitting diode chip, so that it can prevent the connection of the light-emitting diode chip and the silicon base from being affected by the thermal expansion to increase the reliability of the side view type light-emitting diode package structure. In addition, the silicon base has a superior heat-conducting ability, so that a conventional lead frame including a metal heat sink and having a highly irregular thickness is not needed, thereby greatly reducing the difficulty of manufacturing the lead frame and solving the scrap issue occurred in the process of manufacturing the lead frame. Furthermore, a silicon base has a superior heat-conducting property, so that the package structure is suitable for a low-power light-emitting diode chip and a high-power light-emitting diode chip of more than 1 W. Moreover, the cavity surface of a silicon base is smooth when formed using a semiconductor process, so that the surface of the cavity can be used as a reflective surface directly, the reflective effect of the reflective surface is not affected by the plasma cleaning, and the silicon base has a better reflective effect than the conventional plastic base. 
     The aforementioned side view type light-emitting diode package structures can be applied in a light-emitting diode light bar and a light-emitting diode backlight module. The light-emitting diode package structures are side view type, so that the width of the light-emitting diode light bar and the thickness of the side-edged type backlight module can be effectively reduced. 
     Refer to  FIG. 8 .  FIG. 8  is a schematic diagram showing a light-emitting diode backlight module in accordance with a preferred embodiment of the present invention. A light-emitting diode backlight module  252  mainly includes a carrier  260 , a light guide plate  254  and at least one light-emitting diode light bar  250 . The carrier  260  may be a frame structure or a plate structure. The material of the carrier  260  may be metal or a hard plastic material to provide support with sufficient strength. The light guide plate  254  is disposed on the carrier  260 . In the present exemplary embodiment, the light guide plate  254  is a wedge-shaped plate with an uneven thickness. Certainly, the light-emitting diode backlight module  252  may adopt a flat light guide plate with a uniform thickness. The light-emitting diode light bar  250  is also disposed on the carrier  260  and is located beside a light-entering surface  262  of the light guide plate  254 . 
     In the present exemplary embodiment, the light-emitting diode light bar  250  is an application of the side view type light-emitting diode package structure  200 . Therefore, the light-emitting diode light bar  250  mainly includes at least one side view type light-emitting diode package structure  200  and a circuit board  248 . The side view type light-emitting diode package structure  200  is disposed on a plane surface  264  of the circuit board  248 , and the conductive leads  218  of the side view type light-emitting diode package structure  200  are attached to the plane surface  264  of the circuit board  248 . The plane surface  264  of the circuit board  248  is preset with a circuit, and the conductive leads  218  are electrically connected to the circuit preset on the plane surface  264  of the circuit board  248  to further electrically connect the light-emitting diode chip  212  in the side view type light-emitting diode package structure  200  to the circuit board  248 . In the light-emitting diode light bar  250 , the light-extracting surface  224  of the side view type light-emitting diode package structure  200  is substantially perpendicular to the plane surface  264  of the circuit board  248 . In addition, when the light-emitting diode light bar  250  is applied in the light-emitting diode backlight module  252 , the light-extracting surface  224  of the side view type light-emitting diode package structure  200  of the light-emitting diode light bar  250  is opposite to the light-entering surface  262  of the light guide plate  254 . 
     In one exemplary embodiment, according to the brightness requirement of the product, the light-emitting diode backlight module  252  may selectively include a reflective sheet  256  disposed between the light guide plate  254  and the carrier  260 . In addition, the light-emitting diode backlight module  252  may selectively include one or more optical films, such as a brightness enhancement film and a diffusion sheet, to enhance the optical quality of the light-emitting diode backlight module  252 . 
     Refer to  FIG. 9 .  FIG. 9  is a schematic diagram showing a light-emitting diode backlight module in accordance with another preferred embodiment of the present invention. A light-emitting diode backlight module  252   a  mainly includes a carrier  260 , a light guide plate  254   a  and at least one light-emitting diode light bar  250   a.  The light guide plate  254   a  is disposed on the carrier  260 . In the present exemplary embodiment, the light guide plate  254   a  is a flat light guide plate with a uniform thickness. However, the aforementioned wedge-shaped light guide plate  254  with an uneven thickness may be adopted in the light-emitting diode backlight module  252   a.  The light-emitting diode light bar  250   a  is also disposed on the carrier  260  and is located beside a light-entering surface  262   a  of the light guide plate  254   a.    
     In the present exemplary embodiment, the light-emitting diode light bar  250   a  is an application of the side view type light-emitting diode package structure  200   a.  Therefore, the light-emitting diode light bar  250   a  mainly includes at least one side view type light-emitting diode package structure  200   a  and a circuit board  248   a.  The side view type light-emitting diode package structure  200   a  is disposed on a plane surface  264   a  of the circuit board  248   a,  and the conductive leads  218   a  of the side view type light-emitting diode package structure  200   a  are attached to the plane surface  264   a  of the circuit board  248   a.  The plane surface  264   a  of the circuit board  248   a  is preset with a circuit, and the conductive leads  218   a  are electrically connected to the circuit preset on the plane surface  264   a  of the circuit board  248   a  to further electrically connect the light-emitting diode chip  212   a  in the side view type light-emitting diode package structure  200   a  to the circuit board  248   a.  In the light-emitting diode light bar  250   a,  the light-extracting surface  224  of the side view type light-emitting diode package structure  200   a  is substantially perpendicular to the plane surface  264   a  of the circuit board  248   a.  When the light-emitting diode light bar  250   a  is applied in the light-emitting diode backlight module  252   a,  the light-extracting surface  224  of the side view type light-emitting diode package structure  200   a  of the light-emitting diode light bar  250   a  is opposite to tie light-entering surface  262   a  of the light guide plate  254   a.    
     In one exemplary embodiment, according to the brightness requirement of the product, the light-emitting diode backlight module  252   a  may selectively include a reflective sheet  256  disposed between the light guide plate  254   a  and the carrier  260 . In addition, the light-emitting diode backlight module  252   a  may selectively include one or more optical films, such as a brightness enhancement film and a diffusion sheet, to enhance the optical quality of the light-emitting diode backlight module  252   a.    
     As is understood by a person skilled in the art, the foregoing embodiments of the present invention are illustrative of the present invention rather than limiting of the present invention. It is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims, the scope of which should be accorded the broadest interpretation so as to encompass all such modifications and similar structure.