Patent Publication Number: US-2015069425-A1

Title: Light-emitting device module and method of manufacturing same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2013-0108063, filed on Sep. 9, 2013, in the Korean Intellectual Property Office, the disclosure of which is incorporated by reference herein in its entirety. 
     1. TECHNICAL FIELD 
     Exemplary embodiments of the present invention relate to a light-emitting device module, and more particularly to a method of manufacturing the same. 
     2. DISCUSSION OF RELATED ART 
     Light-emitting devices have been used as, for example, a light source for a backlight unit in display devices. Light-emitting devices may be packaged in various forms before being assembled with a backlight module. The backlight unit may include a packaged light-emitting device package. 
     For example, the light-emitting device may be mounted on a lead frame including first and second leads. The first and second leads may be individually connected to the light-emitting device by wires and packaged. The light-emitting device package may be used as a light source for a backlight unit or the like. 
     SUMMARY 
     To manufacture a light-emitting device package, a process of individually connecting the first and second leads to the light-emitting device by wires may be used. When the lead frame including the first and second leads is prepared, a large amount of copper may be used to form the lead frame including the first and second leads. The lead frame may be formed by forming a copper layer on an entire surface of a substrate and removing a portion of the copper layer through patterning of the copper layer. 
     One or more exemplary embodiments of the present invention include a light-emitting device module for realizing a high-resolution display with reduced manufacturing costs and a reduced size and a method of manufacturing the same. The exemplary embodiments of the present invention are only illustrative, and the scope of the present invention is not limited thereto. 
     Exemplary embodiments of the present invention will be set forth in the description which follows and additional aspects of the present invention, in part, will be apparent from the description, or may be learned by practice of the exemplary embodiments. 
     According to one or more exemplary embodiments of the present invention, a light-emitting device module includes a substrate and a light-emitting device disposed on the substrate. The light-emitting display device has a first pad and a second pad disposed thereon. A coating layer covers the light-emitting device. The coating layer has a first via hole and a second via hole configured to respectively expose the first pad and the second pad therethrough. Wirings are configured to be electrically connected to the first pad and the second pad through the first via hole and the second via hole. The wirings are disposed on the coating layer. 
     According to an exemplary embodiment of the present invention, the coating layer may cover the entire surface of the substrate. 
     According to an exemplary embodiment of the present invention, the light-emitting device module may include an adhesive. The adhesive may be configured to fix the light-emitting device onto the substrate. 
     According to an exemplary embodiment of the present invention, the wirings may include copper (Cu). 
     According to an exemplary embodiment of the present invention, each of the wiring may include a first wiring layer configured to be electrically connected to the first pad or the second pad through the first via hole or the second via hole. The first wiring layer may be disposed on the coating layer. A second wiring layer may be disposed on the first wiring layer. 
     According to an exemplary embodiment of the present invention, the first wiring layer may include silver (Ag), and the second wiring layer may include Cu. The second wiring layer need not be located in the first via hole and the second via hole. 
     According to an exemplary embodiment of the present invention, the substrate and the coating layer may include a same material. The substrate and the coating layer may be a single body. 
     According to an exemplary embodiment of the present invention, the coating layer may include a light-transmitting material. 
     According to an exemplary embodiment of the present invention, the coating layer may include polyimide. 
     According to one or more exemplary embodiments of the present invention, a light-emitting device module includes a plurality of light-emitting devices disposed on a substrate. Each of the light-emitting devices is separated from each other. Each of the light-emitting devices has a first pad and a second pad disposed thereon. The light-emitting device module includes a film wrapping the plurality of light-emitting devices. The film has first via holes and second via holes configured to respectively expose the first pads and the second pads of the plurality of light-emitting devices. Wirings are disposed on the film. The wirings are configured to be electrically connected to the first pads and the second pads through the first via holes and the second via holes. 
     According to one or more exemplary embodiments of the present invention, a method of manufacturing a light-emitting device module includes disposing a light-emitting device having a first pad and a second pad on a substrate. A coating layer is formed to cover the light-emitting device. A first via hole and a second via hole are formed in the coating layer to respectively expose the first pad and the second pad of the light-emitting device therethrough. Wirings are formed on the coating layer. The wirings are electrically connected to the first pad and the second pad of the light-emitting device. 
     According to an exemplary embodiment of the present invention, the forming of the coating layer may include forming the coating layer to cover the entire surface of the substrate. 
     According to an exemplary embodiment of the present invention, the disposing of the light-emitting device may include disposing the light-emitting device by fixing the light-emitting device onto the substrate with an adhesive. 
     According to an exemplary embodiment of the present invention, the forming of the wirings on the coating layer may include printing a copper (Cu) paste on the coating layer to contact the first pad and the second pad of the light-emitting device. 
     According to an exemplary embodiment of the present invention, the forming of the wirings on the coating layer may include forming a first wiring layer by printing a paste including a first conductive material on the coating layer to contact the first pad and the second pad of the light-emitting device. The forming of the wirings on the coating layer may include forming a second wiring layer on the first wiring layer by plating a second conductive material on the first wiring layer. The first conductive material may include silver (Ag), and the second conductive material may include Cu. 
     According to an exemplary embodiment of the present invention, the first conductive material may include silver (Ag), and the second conductive material may include copper (Cu). 
     According to an exemplary embodiment of the present invention, the forming of the coating layer may include forming the coating layer using a same material as the substrate. 
     According to an exemplary embodiment of the present invention, the coating layer may include a light-transmitting material. 
     According to an exemplary embodiment of the present invention, the coating layer may include polyimide. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features of the present invention will become more apparent by describing in detail exemplary embodiments thereof, with reference to the accompanying drawings in which: 
         FIGS. 1 to 4  are schematic cross-sectional views illustrating a method of manufacturing a light-emitting device module according to an exemplary embodiment of the present invention; 
         FIG. 5  is a schematic cross-sectional view of a light-emitting device module manufactured by a method according to an exemplary embodiment of the present invention; and 
         FIG. 6  is a schematic perspective view of a light-emitting device module according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention should not be construed as limited to the exemplary embodiments set forth herein and may be embodied in different forms. Like reference numerals may refer to the like elements. 
     It will be understood that when a layer, region, or component is referred to as being “formed on,” another layer, region, or component, it may be directly or indirectly formed on the other layer, region, or component. For example, intervening layers, regions, or components may be present. 
     Sizes of elements in the drawings may be exaggerated for convenience of explanation. Sizes and thicknesses of components in the drawings may be arbitrarily illustrated for convenience of explanation and the following exemplary embodiments of the present invention are not limited thereto. 
     In the following examples, the x-axis, the y-axis and the z-axis may not be limited to three axes of the rectangular coordinate system, and may be interpreted in a broader sense. For example, the x-axis, the y-axis, and the z-axis may be perpendicular to one another, or may represent different directions that are not perpendicular to one another. 
       FIGS. 1 to 4  are schematic cross-sectional views illustrating a method of manufacturing a light-emitting device module according to an exemplary embodiment of the present invention. 
     According to the method of manufacturing a light-emitting device module according to an exemplary embodiment of the present invention, a light-emitting device  20  is disposed on a substrate  10  as shown in  FIG. 1 , for example. The light-emitting device  20  may be disposed on the substrate  10  by fixing the light-emitting device  20  onto the substrate  10  by an adhesive  30  as shown in  FIG. 1 , for example. The adhesive  30  may be interposed between the light-emitting device  20  and the substrate  10 . As shown in  FIG. 1 , for example, the adhesive  30  may be disposed around the light-emitting device  20 . 
     For example, the substrate  10  may include polyimide. For example, an FR4 substrate or a CEM-3 substrate used as a printed circuit board may be used. When a polyimide substrate is used as the substrate  10 , a flexible light-emitting device module may be formed, for example. 
     The light-emitting device  20  may be a device for emitting light by receiving an electrical signal and may be used as a light source for various electronic devices. For example, the light-emitting device  20  may include a diode of a compound semiconductor. The light-emitting device  20  may be referred to as a light-emitting diode (LED). The LED may emit light of various wavelengths, for example, according to materials of the compound semiconductor. The light-emitting device  20  may have a first pad  21  and a second pad  22 . The first pad  21  and/or the second pad  22  may receive an electrical signal. 
     After disposing the light-emitting device  20  on the substrate  10 , a coating layer  40  may be formed. The coating layer  40  may cover the light-emitting device  20 , as shown in  FIG. 2 , for example. The coating layer  40  may include a light-transmitting material, for example, polyimide, epoxy, or the like. The coating layer  40  may be formed by a spin coating method. For example, by using the spin coating method, the coating layer  40  covering the light-emitting device  20  and the entire surface of the substrate  10  may be formed. 
     As shown in  FIG. 3 , for example, a first via hole  40   a  and a second via hole  40   b  may be formed in the coating layer  40 . The first via hole  40   a  and the second via hole  40   b  may respectively expose the first pad  21  and the second pad  22  of the light-emitting device  20  therethrough. 
     Various methods may be used to form the first via hole  40   a  and the second via hole  40   b . For example, as shown in  FIG. 3 , the first via hole  40   a  and the second via hole  40   b  may be formed in the coating layer  40  to respectively expose the first pad  21  and the second pad  22  of the light-emitting device  20  therethrough by forming a photoresist layer on the coating layer  40 , light-exposing and developing the photoresist layer to expose only a portion where the first via hole  40   a  and the second via hole  40   b  of the coating layer  40  are to be formed, forming the first via hole  40   a  and the second via hole  40   b  through etching or the like, and removing the remaining photoresist layer. Alternatively, the first via hole  40   a  and the second via hole  40   b  may be formed in the coating layer  40  to respectively expose the first pad  21  and the second pad  22  of the light-emitting device  20  therethrough by removing a portion of the coating layer  40  where the first via hole  40   a  and the second via hole  40   b  of the coating layer  40  are to be formed through irradiation of laser beams only on the portion of the coating layer  40  where the first via hole  40   a  and the second via hole  40   b  are to be formed. 
     When a laser etching method is used, the first via hole  40   a  and the second via hole  40   b  may be formed by the laser etching method so that a portion of the coating layer  40  is not damaged, except the first via hole  40   a  and the second via hole  40   b  of the coating layer  40 . For example, when the coating layer  40  includes polyimide and when laser beams are irradiated thereon, only a portion of the coating layer  40  on which the laser beams are irradiated might be removed, and another portion of the coating layer  40  might not be removed. 
     After forming the first via hole  40   a  and the second via hole  40   b  in the coating layer  40 , as shown in  FIG. 4 , for example, wirings  50  electrically connected to the first pad  21  and the second pad  22  of the light-emitting device  20  may be formed on the coating layer  40 .  FIG. 4  shows, for example, two wirings  50  wherein one wiring  50  is electrically connected to the first pad  21  and the other wiring  50  is electrically connected to the second pad  21 . When at least a portion of the first pad  21  and the second pad  22  of the light-emitting device  20  is exposed due to the existence of the first via hole  40   a  and the second via hole  40   b  in the coating layer  40 , the wirings  50  may contact the first pad  21  and the second pad  22  of the light-emitting device  20  through the first via hole  40   a  and the second via hole  40   b  when the wirings  50  are formed on the coating layer  40 . The wirings  50  may be formed by printing a copper (Cu) paste on the coating layer  40  to contact the first pad  21  and the second pad  22  of the light-emitting device  20 . 
     To manufacture the light-emitting device package of  FIG. 4 , for example, a process of preparing a lead frame including a first lead and a second lead and respectively connecting a first pad  21  and a second pad  22  of a light-emitting device to the first lead and the second lead by wires may be performed. To connect the first lead and the second lead to the light-emitting device by wires, the sizes of the first lead and the second lead may be relatively large, and the total size of the light-emitting device package may be large. 
     According to a method of manufacturing a light-emitting device module according to an exemplary embodiment of the present invention, the process of connecting the first lead and the second lead to the light-emitting device by wires may be skipped. When the wirings  50  are formed in the coating layer  40  by a printing method, for example, the wirings  50  contacting the first pad  21  and the second pad  22  of the light-emitting device  20  through the first via hole  40   a  and the second via hole  40   b  located on the first pad  21  and the second pad  22  may be formed. A space for wirings  50  required for a light-emitting device package may be manufactured according to a method of manufacturing a light-emitting device package according to an exemplary embodiment of the present invention and a total size of the light-emitting device module may be reduced. 
     For example, when a size of a light-emitting device package is relatively large and a display is formed using the light-emitting device package, a pixel size may be large, and a pitch between pixels may be accordingly large, and it may be difficult to implement a high-resolution display. When the size of the light-emitting device module manufactured by the method of manufacturing a light-emitting device module according to exemplary embodiments of the present invention is small, and a high-resolution display may be formed using the light-emitting device module. 
     According to a method of manufacturing a light-emitting device package according to an exemplary embodiment of the present invention, when the lead frame including the first lead and the second lead is prepared, the lead frame including the first lead and the second lead may be formed by forming a Cu layer on the entire surface of a substrate and patterning the Cu layer to remove a portion of the Cu layer. When an amount of Cu removed in a process of forming the lead frame is relatively large, manufacturing costs may be increased. According to the method of manufacturing a light-emitting device module according to an exemplary embodiment of the present invention, when the wirings  50  are formed by a printing method, for example, an amount of a material consumed to form the wirings  50  may be reduced. 
     When the coating layer  40  is formed, the coating layer  40  may include the same material as the substrate  10 . For example, the substrate  10  may include polyimide. For example, the coating layer  40  may be formed by coating polyimide on the substrate  10  by spin coating. The substrate  10  and the coating layer  40  may be a single body. For example, the substrate  10  and the coating layer  40  may be formed integrally, and an interface might not exist therebetween. A light-emitting device module in a form of chip in film may be formed by the method of manufacturing a light-emitting device module according to an exemplary embodiment of the present invention. 
       FIG. 5  is a schematic cross-sectional view of a light-emitting device module manufactured by a method of manufacturing a light-emitting device module according to an exemplary embodiment of the present invention. According to the method of manufacturing the light-emitting device module according to an exemplary embodiment of the present invention, as shown in  FIG. 3 , for example, a first wiring layer  51  may be formed by forming the first via hole  40   a  and the second via hole  40   b  in the coating layer  40  to respectively expose the first pad  21  and the second pad  22  of the light-emitting device  20  therethrough and printing a paste including a first conductive material on the coating layer  40  to contact the first pad  21  and the second pad  22  of the light-emitting device  20 . A second wiring layer  52  may be formed by plating a second conductive material on the first wiring layer  51 . The first conductive material may include, for example, silver (Ag), and the second conductive material may include, for example, Cu. 
     The wirings  50  may be formed by printing a Cu paste on the coating layer  40  to contact the first pad  21  and the second pad  22  of the light-emitting device  20 . When a Cu paste is printed a defective rate may be high. When an Ag paste is formed, as shown in  FIG. 5 , for example, the first wiring layer  51  contacting the first pad  21  and the second pad  22  of the light-emitting device  20  may be formed by a printing method. When the second wiring layer  52  including Cu is formed only on the first wiring layer  51  including Ag by using a seed layer through plating or the like, the conductivity of the wirings  50  may be increased by the second wiring layer  52 , and the waste of Cu may be reduced when the second wiring layer  52  is formed. 
     A light-emitting device module as shown in  FIG. 6 , for example, may be manufactured using a method of manufacturing a light-emitting device module according to an exemplary embodiment of the present invention. A plurality of light-emitting devices  20  may be disposed on the substrate  10 . The coating layer  40  may cover the plurality of light-emitting devices  20 . First via holes  40   a  and second via holes  40   b  may be formed and may respectively expose first pads  21  and second pads  22  of the plurality of light-emitting devices  20 . The wirings  50  may be disposed on the coating layer  40 . A wiring  50   a  may be commonly and electrically connected to each of the first pads  21  of the plurality of light-emitting devices  20 . A wiring  50   b  may be commonly and electrically connected to each of the second pads of the plurality of light-emitting devices  20 . A bar-shaped light-emitting device module having the plurality of light-emitting devices  20  may be formed. When separate wiring is not used, a distance (pitch) between the plurality of light-emitting devices  20  may be reduced, thereby implementing a bar-shaped light-emitting device module capable of emitting light of high brightness with a small size. 
     Although exemplary methods of manufacturing a light-emitting device module according to exemplary embodiments of the present invention have been described, the scope of the present invention is not limited thereto. For example, a light-emitting device module may belong to the scope of the present invention. 
     A light-emitting device module according to an exemplary embodiment of the present invention may have, for example, a shape as shown in  FIG. 4 . The light-emitting device module according to an exemplary embodiment of the present invention may include the substrate  10 , the light-emitting device  20 , the coating layer  40 , and the wirings  50 . 
     The substrate  10  may include, for example, polyimide. The light-emitting device  20  may be disposed on the substrate  10  and may have the first pad  21  and the second pad  22  disposed thereon. The light-emitting device  20  may be fixed to the substrate  10  by the adhesive  30  as shown in  FIG. 1 , for example. The coating layer  40  may cover the light-emitting device  20  and may include the first via hole  40   a  and the second via hole  40   b . The first via hole  40   a  and the second via hole  40   b  may be configured to expose the first pad  21  and the second pad  22  therethrough. The coating layer  40  may include a light-transmitting material, for example, polyimide, epoxy, or the like. The coating layer  40  may cover the light-emitting device  20  and/or the entire surface of the substrate  10 . The wirings  50  may be electrically connected to the first pad  21  and the second pad  22  through the first via hole  40   a  and the second via hole  40   b . The wirings  50  may be disposed on the coating layer  40 . The wirings  50  may include Cu. 
     The light-emitting device package may include a lead frame including a first lead and a second lead, and a first pad  21  and a second pad  22 . The light-emitting device on the lead frame may be connected to the first lead and the second lead of the lead frame by wires. To connect the first lead and the second lead to the light-emitting device by wires, sizes of the first lead and the second lead may be relatively large, and a total size of the light-emitting device package may be relatively large. 
     The light-emitting device module according to an exemplary embodiment of the present invention may not include a connection using wires. For example, when the wirings  50  are formed by a printing method and are located on the coating layer  40 , the wirings  50  may directly contact the first pad  21  and the second pad  22  of the light-emitting device  20  through the first via hole  40   a  and the second via hole  40   b  located on the first pad  21  and the second pad  22 . When a space for wiring does not exist, a total size of the light-emitting device module may be reduced. 
     When the size of the light-emitting device package is large and a display is formed using the light-emitting device package, a pixel size may be large, and a pitch between pixels may be accordingly large and it may be difficult to implement a high-resolution display. When the size of the light-emitting device module according to an exemplary embodiment of the present invention is small, a high-resolution display may be formed using the light-emitting device module. 
     When the lead frame including the first lead and the second lead is prepared, the lead frame including the first lead and the second lead may be formed by forming a Cu layer on the entire surface of a substrate and patterning the Cu layer to remove a portion of the Cu layer. An amount of Cu removed in a process of forming the lead frame may be large, thereby increasing manufacturing costs. In the light-emitting device module according to an exemplary embodiment of the present invention, when the wirings  50  are formed by a printing method, for example, an amount of a material consumed to form the wirings  50  may be reduced. In the light-emitting device module according to an exemplary embodiment of the present invention, costs for manufacturing the light-emitting device module may be reduced. 
     The substrate  10  and the coating layer  40  may include a same material. For example, the substrate  10  may include a polyimide. The coating layer  40  may be formed by spin-coating a polyimide. The substrate  10  and the coating layer  40  may be a single body, and an interface might not exist therebetween. The light-emitting device module according to an exemplary embodiment of the present invention may be a chip in film light-emitting device module. 
     In a light-emitting device module according to an exemplary embodiment of the present invention, the wirings  50  may include the first wiring layer  51  and the second wiring layer  52  as shown in  FIG. 5 , for example. The first wiring layer  51  may be electrically connected to the first pad  21  and the second pad  22  through the first via hole  40   a  and the second via hole  40   b . The first wiring layer  51  may be disposed on the coating layer  40 . The second wiring layer  52  may be disposed on the first wiring layer  51 . The first wiring layer  51  may be formed by printing a paste including the first conductive material on the coating layer  40  to contact the first pad  21  and the second pad  22  of the light-emitting device  20 . The second wiring layer  52  may be formed by plating the second conductive material on the first wiring layer  51 . The first conductive material may include, for example, Ag, and the second conductive material may include, for example, Cu. 
     The wirings  50  may be formed by printing a Cu paste on the coating layer  40  to contact the first pad  21  and the second pad  22  of the light-emitting device  20 . The Cu paste may be difficult to form, and when the Cu paste is formed, a defect rate may be high. An Ag paste may be easier to manufacture and easier to print. For example, when the Ag paste is used, as shown in  FIG. 5 , the first wiring layer  51  contacting the first pad  21  and the second pad  22  of the light-emitting device  20  may be formed by a printing method. For example, when the second wiring layer  52  including Cu is formed on the first wiring layer  51  including Ag by using a seed layer through plating or the like, the conductivity of the wirings  50  may be increased by the second wiring layer  52 . The waste of Cu may be reduced when the second wiring layer  52  is formed. 
     In the light-emitting device module according to an exemplary embodiment of the present invention, when the second wiring layer  52  may be formed using the first wiring layer  51  as a seed layer through a plating method, the second wiring layer  52  may not be disposed in the first via hole  40   a  and the second via hole  40   b  because the first wiring layer  51  is disposed in the first via hole  40   a  and the second via hole  40   b.    
       FIG. 6  is a schematic perspective view of a light-emitting device module according to an exemplary embodiment of the present invention. As shown in  FIG. 6 , the light-emitting device module according to an exemplary embodiment of the present invention may have a structure in which a plurality of light-emitting devices  20  are disposed on the substrate  10 . The coating layer  40  may cover the plurality of light-emitting devices  20 . The coating layer  40  may have first via holes  40   a  and second via holes  40   b . The first via holes  40   a  and second via holes  40   b  may respectively expose first pads  21  and second pads  22  of the plurality of light-emitting devices  20 . The wirings  50  may be located on the coating layer  40 . The wirings  50  may include a wiring  50   a  and a wiring  50   b , wherein the wiring  50   a  is commonly and electrically connected to each of the first pads  21  of the plurality of light-emitting devices  20 . The wiring  50   b  may be commonly and electrically connected to each of the second pads  22  of the plurality of light-emitting devices  20 . 
     The light-emitting device module according to an exemplary embodiment of the present invention may include the plurality of light-emitting devices  20  separated from each other and having the first pads  21  and the second pads  22 . The substrate  10  and/or the coating layer  40  may wrap the plurality of light-emitting devices  20  to be located therein. The substrate  10  and/or the coating layer  40  may have the first via holes  40   a  and the second via holes  40   b  formed therein. The first via holes  40   a  and the second via holes  40   b  may respectively expose first pads  21  and second pads  22  of the plurality of light-emitting devices  20  therethrough. The wirings  50  may be electrically connected to the first pads  21  and the second pads  22  through the first via holes  40   a  and the second via holes  40   b . The wirings  50  may be disposed on the substrate  10  and/or the coating layer  40 . 
     According to the exemplary embodiments described above, a bar-shaped light-emitting device module having the plurality of light-emitting devices  20  may be formed. For example, when separate wiring steps are not needed, a distance (pitch) between the plurality of light-emitting devices  20  may be reduced and a bar-shaped light-emitting device module capable of emitting light of high brightness with a small size may be formed. 
     As described above, according to one or more of the above exemplary embodiments of the present invention, a light-emitting device module for a high-resolution display with reduced manufacturing costs and a reduced size may be formed and a method of manufacturing the same may be performed. The scope of the present invention is not limited to effects thereof. 
     While the present invention has been shown and described with reference to the exemplary embodiments thereof, it will be apparent to those of ordinary skill in the art that various changes in form and detail may be made thereto without departing from the spirit and scope of the present invention.