Patent Publication Number: US-2015076542-A1

Title: Light emitting module

Description:
RELATED APPLICATIONS 
     This application claims priority to Taiwan Application Serial Number 102133407, filed Sep. 14, 2013, which is herein incorporated by reference. 
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a light emitting module. 
     2. Description of Related Art 
     A conventional light emitting module undergoes a curing process after a die-bonding process. The curing process often results in a peeling-off phenomenon due to high temperature.  FIG. 1  is a cross-sectional view showing the peeling-off phenomenon of a conventional light emitting module. During the curing process, fluorescent glue  800  is heated and expands toward a direction  700 . Because an adhesion force between the fluorescent glue  800  and a chip  900  is generally greater than that between the chip  900  and a bonding layer  920 , when the fluorescent glue  800  expands toward the direction  700 , the fluorescent glue  800  pulls the chip  900  to move toward the direction  700 . As a result, the chip  900  peels off from the bonding layer  920 , and a gap  600  is formed therebetween. Thus, the light emitting module is scrapped and cannot be reworked. 
     SUMMARY 
     The present disclosure provides a light emitting module including a base board, a light emitting diode chip, a transparent thermoplastic layer, and fluorescent glue. The base board includes a die-bonding zone, which is predetermined. The light emitting diode chip is bonded on the die-bonding zone. The light emitting diode chip includes an upper surface, a lower surface opposite to the upper surface, and a plurality of side surfaces adjoined between the upper surface and lower surfaces. A transparent thermoplastic layer encloses at least one portion of the light emitting diode chip. The fluorescent glue disposed over to cover the base board, the light emitting diode chip, and the transparent thermoplastic layer. 
     In an embodiment of the present disclosure, the base board is a metal frame. 
     In an embodiment of the present disclosure, the light emitting module further includes a package cup body partially enclosing the metal frame, and exposing a part of a surface of the metal frame. The part of the surface of the metal frame being configured to be the die-bonding zone. 
     In an embodiment of the present disclosure, the light emitting module further includes a bonding material configured to bond the light emitting diode chip on the die-bonding zone. The bonding material includes tin, copper-tin alloy, or gold-tin alloy. 
     In an embodiment of the present disclosure, when the light emitting diode chip is bonded on the die-bonding zone through the upper surface, the transparent thermoplastic layer fully encloses the lower surface and the side surfaces of the light emitting diode chip. When the light emitting diode chip is bonded on the die-bonding zone through the lower surface, the transparent thermoplastic layer fully encloses the upper surface and the side surfaces of the light emitting diode chip. 
     In an embodiment of the present disclosure, when the transparent thermoplastic layer partially encloses the light emitting diode chip, the transparent thermoplastic layer is coated at a junction of the base board and at least one of the side surfaces of the light emitting diode chip. Therefore, at least one portion of a bottom edge of the at least one of the side surfaces and a surface of the base board adjacent to the bottom edge are enclosed by the transparent thermoplastic layer. 
     In an embodiment of the present disclosure, the package cup body is made of a thermoplastic material or a thermoset material. 
     In an embodiment of the present disclosure, the thermoplastic material is polycarbonate, polyethylene, polyethylene terephthalate, polybutylene terephthalate, poly 1,4-cyclohexylene dimethylene terephthalate, polycarbonate, polypropylene, nylon, or combinations thereof. 
     In an embodiment of the present disclosure, the thermoset material is silicone, epoxy, acrylate, acrylic, or combinations thereof. 
     In an embodiment of the present disclosure, the transparent thermoplastic layer is polycarbonate, polyethylene, polyethylene terephthalate, polybutylene terephthalate, poly 1,4-cyclohexylene dimethylene terephthalate, polycarbonate, polypropylene, nylon, or combinations thereof. 
     In an embodiment of the present disclosure, the fluorescent glue includes fluorescent powder and a thermoplastic of silicone, epoxy, acrylate, acrylic, or combinations thereof. 
     In an embodiment of the present disclosure, the fluorescent glue further includes a light scattering material having less than 0.1 wt % of one of titanium dioxide, silica, zinc oxide, alumina, or combination thereof. 
     Accordingly, the light emitting module of the disclosure includes the transparent thermoplastic layer. When the light emitting module goes through a curing process, the fluorescent glue expands upward. In the meantime, the transparent thermoplastic layer is softened by heat, such that the transparent thermoplastic layer becomes a buffer layer between the fluorescent glue and the light emitting diode chip. When the fluorescent glue expands upward, the light emitting diode chip will not be pulled upward due to the buffer layer, thus preventing a peeling-off phenomenon. As a result, the production yield is increased and the production cost is decreased. 
     It is to be understood that both the foregoing general description and the following detailed description are by examples, and are intended to provide further explanation of the disclosure as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure can be more fully understood by reading the following detailed description of the embodiment, with reference made to the accompanying drawings as follows: 
         FIG. 1  illustrates a cross-sectional view showing a peeling-off phenomenon of a conventional light emitting module; 
         FIG. 2  illustrates a cross-sectional view of a light emitting module according to an embodiment of the present disclosure; 
         FIG. 3  illustrates a cross-sectional view of a light emitting module according to another embodiment of the present disclosure; 
         FIG. 4  illustrates a top view of a light emitting module according to an embodiment of the present disclosure; 
         FIG. 5  illustrates a top view of a light emitting module according to another embodiment of the present disclosure; 
         FIG. 6  illustrates a top view of a light emitting module according to another embodiment of the present disclosure; 
         FIG. 7  illustrates a top view of a light emitting module according to another embodiment of the present disclosure; 
         FIG. 8  illustrates a top view of a light emitting module according to another embodiment of the present disclosure; 
         FIG. 9  illustrates a top view of a light emitting module according to another embodiment of the present disclosure; 
         FIG. 10  illustrates a top view of a light emitting module according to another embodiment of the present disclosure; 
         FIG. 11  illustrates a top view of a light emitting module according to another embodiment of the present disclosure; and 
         FIG. 12  illustrates a top view of a light emitting module according to another embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Reference will now be made in detail to the present embodiments of the disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the description to refer to the same or like parts. 
     In order to solve the peeling-off problem of the conventional light emitting module, the disclosure provides a light emitting module to effectively improve the problem.  FIG. 2  illustrates a cross-sectional view of a light emitting module  100  according to an embodiment of the present disclosure. The disclosure provides the light emitting module  100  including a base board  110 , a light emitting diode chip  130 , a transparent thermoplastic layer  140 , and fluorescent glue  150 . The base board  110  includes a die-bonding zone  120 . The light emitting diode chip  130  is bonded on the die-bonding zone  120 . The light emitting diode chip  130  includes an upper surface  132 , a lower surface  134  opposite to the upper surface  132 , and side surfaces  136  adjoined between the upper surface  132  and the lower surface  134 . The transparent thermoplastic layer  140  encloses at least one portion of the light emitting diode chip  130 . The fluorescent glue  150  is disposed over to cover the base board  110 , the light emitting diode chip  130 , and the transparent thermoplastic layer  140 . The base board  110  is a metal frame. The light emitting module  100  further includes a package cup body  160  partially enclosing the metal frame and exposing a portion of a surface of the metal frame. The portion of the surface of the metal frame is configured as the die-bonding zone  120 . A bonding material  170  is disposed below the light emitting diode chip  130  to bond the light emitting diode chip  130  on the die-bonding zone  120 . The bonding material  170  may include tin, copper-tin alloy, or gold-tin alloy. When the light emitting diode chip  130  is bonded on the die-bonding zone  120  through the lower surface  134 , the transparent thermoplastic layer  140  entirely encloses the upper surface  132  and the side surfaces  136  of the light emitting diode chip  130 . 
       FIG. 3  illustrates a sectional view of a light emitting module  100 ′ according to another embodiment of the present disclosure. In an embodiment of the present disclosure, the light emitting diode chip  130  of the light emitting module  100 ′ is bonded on the die-bonding zone  120  with the upper surface  132 . The transparent thermoplastic layer  140  entirely encloses the lower surface  134  and the side surfaces  136  of the light emitting diode chip  130 . In this embodiment, the method of bonding the light emitting diode chip  130  is referred to a flip chip method, in which the base board  110  and the upper surface  132  are electrically connected with the bonding material  170 . In an embodiment, the package cup body  160  is made of a thermoplastic material or a thermoset material. The thermoplastic material may be polycarbonate, polyethylene, polyethylene terephthalate, polybutylene terephthalate, poly 1,4-cyclohexylene dimethylene terephthalate, polycarbonate, polypropylene, nylon, or combinations thereof. The thermoset material may be silicone, epoxy, acrylate oracrylic, or combinations thereof. The transparent thermoplastic layer  140  may be polycarbonate, polyethylene, polyethylene terephthalate, polybutylene terephthalate, poly 1,4-cyclohexylene dimethylene terephthalate, polycarbonate, polypropylene, nylon, or combinations thereof. The fluorescent glue  150  includes fluorescent powder and a thermoplastic made of silicone, epoxy, acrylate, acrylic, or combinations thereof. In an embodiment, the fluorescent glue  150  further includes a light scattering material having less than 0.1 wt % of one of titanium dioxide, silica, zinc oxide, alumina, or combination thereof. In an embodiment, the transparent thermoplastic layer  140  is softened between 150 and 250 Celsius degrees and becomes a molten state. When the light emitting module  100 ′ undergoes a high temperature curing process, the fluorescent glue  150  expands upward. In the meantime, the transparent thermoplastic layer  140  is softened by heat, such that the transparent thermoplastic layer  140  becomes a buffer layer between the fluorescent glue  150  and the light emitting diode chip  130 . When the fluorescent glue  150  expands upward, the light emitting diode chip  130  will not be pulled upward due to the buffer layer. Hence, the peeling-off phenomenon can be prevented. 
       FIG. 4  illustrates a top view of a light emitting module according to an embodiment of the present disclosure. In an embodiment, the transparent thermoplastic layer  140  is coated at a junction of the base board  110  and one side surface  136  of the light emitting diode chip  130 , such that the bottom edge of one side surface  136  is enclosed by the transparent thermoplastic layer  140 . When the light emitting module undergoes a high temperature curing process, the fluorescent glue expands upward. In the meantime, the transparent thermoplastic layer  140  is softened by heat, such that the transparent thermoplastic layer  140  becomes a buffer layer between the fluorescent glue and the light emitting diode chip  130 . When the fluorescent glue expands upward, the light emitting diode chip  130  will not be pulled upward due to the buffer layer. Hence, the peeling-off phenomenon can be prevented. 
       FIG. 5  illustrates a top view of a light emitting module according to another embodiment of the present disclosure. In an embodiment, the transparent thermoplastic layer  140  is coated at the junctions of the base board  110  and two side surfaces  136  of the light emitting diode chip  130 , such that the bottom edges of two side surfaces  136  are enclosed by the transparent thermoplastic layer  140 . When the light emitting module undergoes a high temperature curing process, the fluorescent glue expands upward. In the meantime, the transparent thermoplastic layer  140  is softened by heat, such that the transparent thermoplastic layer  140  becomes a buffer layer between the fluorescent glue and the light emitting diode chip  130 . When the fluorescent glue expands upward, the light emitting diode chip  130  will not be pulled upward due to the buffer layer. Hence, the peeling-off phenomenon can be prevented. 
       FIG. 6  illustrates a top view of a light emitting module according to another embodiment of the present disclosure. In an embodiment of the present disclosure, the transparent thermoplastic layer  140  is coated at the junctions of the base board  110  and three side surfaces  136  of the light emitting diode chip  130 , such that the bottom edges of three side surfaces  136  are enclosed by the transparent thermoplastic layer  140 . When the light emitting module undergoes a high temperature curing process, the fluorescent glue expands upward. In the meantime, the transparent thermoplastic layer  140  is softened by heat, such that, the transparent thermoplastic layer  140  becomes a buffer layer between the fluorescent glue and the light emitting diode chip  130 . When the fluorescent glue expands upward, the light emitting diode chip  130  will not be pulled upward due to the buffer layer. Hence, the peeling-off phenomenon can be prevented. 
       FIG. 7  illustrates a top view of a light emitting module according to another embodiment of the present disclosure. In an embodiment of the present disclosure, the transparent thermoplastic layer  140  is coated at the junctions of the base board  110  and all side surfaces  136  of the light emitting diode chip  130 , such that the bottom edges of all side surfaces  136  are enclosed by the transparent thermoplastic layer  140 . When the light emitting module undergoes a high temperature curing process, the fluorescent glue expands upward. In the meantime, the transparent thermoplastic layer  140  is softened by heat, such that, the transparent thermoplastic layer  140  becomes a buffer layer between the fluorescent glue and the light emitting diode chip  130 . When the fluorescent glue expands upward, the light emitting diode chip  130  will not be pulled upward due to the buffer layer. Hence, the peeling-off phenomenon can be prevented. 
       FIG. 8  illustrates a top view of a light emitting module according to another embodiment of the present disclosure. In an embodiment of the present disclosure, the transparent thermoplastic layer  140  is coated at the junctions of the base board  110  and all side surfaces  136  of the light emitting diode chip  130 , and the surfaces of the base board  110  near the light emitting diode chip  130 , such that the bottom edges of all side surfaces  136  the surfaces of the base board  110  near the light emitting diode chip  130  are enclosed by the transparent thermoplastic layer  140 . When the light emitting module undergoes a high temperature curing process, the fluorescent glue expands upward. In the meantime, the transparent thermoplastic layer  140  is softened by heat, such that, the transparent thermoplastic layer  140  becomes a buffer layer between the fluorescent glue and the light emitting diode chip  130 . When the fluorescent glue expands upward, the light emitting diode chip  130  will not be pulled upward due to the buffer layer. Hence, the peeling-off phenomenon can be prevented. 
       FIG. 9  illustrates a top view of a light emitting module according to another embodiment of the present disclosure. In an embodiment of the present disclosure, the transparent thermoplastic layer  140  is coated at a part of the junction of the base board  110  and one side surface  136  of the light emitting diode chip  130 , such that a part of the bottom edge of one side surface  136  is enclosed by the transparent thermoplastic layer  140 . When the light emitting module undergoes a high temperature curing process, the fluorescent glue expands upward. In the meantime, the transparent thermoplastic layer  140  is softened by heat, such that, the transparent thermoplastic layer  140  becomes a buffer layer between the fluorescent glue and the light emitting diode chip  130 . When the fluorescent glue expands upward, the light emitting diode chip  130  will not be pulled upward due to the buffer layer. Hence, the peeling-off phenomenon can be prevented. 
       FIG. 10  illustrates a top view of a light emitting module according to another embodiment of the present disclosure. In an embodiment of the present disclosure, the transparent thermoplastic layer  140  is coated at parts of the junctions of the base board  110  and two side surfaces  136  of the light emitting diode chip  130 , such that parts of the bottom edges of two side surfaces  136  are enclosed by the transparent thermoplastic layer  140 . When the light emitting module undergoes a high temperature curing process, the fluorescent glue expands upward. In the meantime, the transparent thermoplastic layer  140  is softened by heat, such that, the transparent thermoplastic layer  140  becomes a buffer layer between the fluorescent glue and the light emitting diode chip  130 . When the fluorescent glue expands upward, the light emitting diode chip  130  will not be pulled upward due to the buffer layer. Hence, the peeling-off phenomenon can be prevented. 
       FIG. 11  illustrates a top view of a light emitting module according to another embodiment of the present disclosure. In an embodiment of the present disclosure, the transparent thermoplastic layer  140  is coated at parts of the junctions of the base board  110  and three side surfaces  136  of the light emitting diode chip  130 , such that parts of the bottom edges of three side surfaces  136  are enclosed by the transparent thermoplastic layer  140 . When the light emitting module undergoes a high temperature curing process, the fluorescent glue expands upward. In the meantime, the transparent thermoplastic layer  140  is softened by heat, such that, the transparent thermoplastic layer  140  becomes a buffer layer between the fluorescent glue and the light emitting diode chip  130 . When the fluorescent glue expands upward, the light emitting diode chip  130  will not be pulled upward due to the buffer layer. Hence, the peeling-off phenomenon can be prevented. 
       FIG. 12  illustrates a top view of a light emitting module according to another embodiment of the present disclosure. In an embodiment of the present disclosure, the transparent thermoplastic layer  140  is coated at part of the junctions of the base board  110  and all side surfaces  136  of the light emitting diode chip  130 , such that parts of the bottom edges of all side surfaces  136  and the base board  110  near thereof are enclosed by the transparent thermoplastic layer  140 . When the light emitting module undergoes a high temperature curing process, the fluorescent glue expands upward. In the meantime, the transparent thermoplastic layer  140  is softened by heat, such that the transparent thermoplastic layer  140  becomes a buffer layer between the fluorescent glue and the light emitting diode chip  130 . When the fluorescent glue expands upward, the light emitting diode chip  130  will not be pulled upward due to the buffer layer. Hence, the peeling-off phenomenon can be prevented. 
     Accordingly, the light emitting module of the disclosure includes the transparent thermoplastic layer. When the light emitting module goes through a curing process, the fluorescent glue expands upward. In the meantime, the transparent thermoplastic layer is softened by heat, such that the transparent thermoplastic layer becomes a buffer layer between the fluorescent glue and the light emitting diode chip. When the fluorescent glue expands upward, the light emitting diode chip will not be pulled upward due to the buffer layer, thus preventing a peeling-off phenomenon. As a result, the production yield is increased and the production cost is decreased. 
     Although the present disclosure has been described in considerable detail with reference to certain embodiments thereof, other embodiments are possible. Therefore, the spirit and scope of the appended claims should not be limited to the description of the embodiments contained herein. 
     It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present disclosure without departing from the scope or spirit of the disclosure. In view of the foregoing, it is intended that the present disclosure cover modifications and variations of this disclosure provided they fall within the scope of the following claims.