Patent Publication Number: US-2016233394-A1

Title: Light emitting diode package

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a continuation of co-pending U.S. application Ser. No. 13/088,513, filed on Apr. 18, 2011, for which priority is claimed under 35 U.S.C. §120; and this application claims priority of Application No. 099147331 filed in Taiwan on Dec. 31, 2010 under 35 U.S.C. §119; the entire disclosure of all of which are hereby incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The invention relates generally to a light emitting diode (LED) device and a method for manufacturing the same, and more particularly, relates to a LED package utilizing an in-mold decoration film and a method for manufacturing the same. 
     BACKGROUND OF THE INVENTION 
     Because energy-saving issue has been getting more and more attention, LED illumination has now become one of the popular lighting applications.  FIGS. 1 to 3  are schematic views respectively illustrating three conventional LED packages packaged by different methods.  FIG. 1  illustrates a LED package  100  packaged by a traditional uniform distribution method. 
     As shown in  FIG. 1 , the phosphor  101  (including red, green or yellow phosphor) packaged by a traditional uniform distribution method can be uniformly distributed in a molding compound  102  molded on a substrate  104 . However, as the distribution of the phosphor  101  cannot be controlled very uniformly, it is difficult for the traditional method to make an LED package  100  having high color uniformity and high outputting lumen. To solve these problems, an electrophoresis coating technique is utilized to distribute the phosphor  101  around the LED die  103  in order to form a conformal distribution structure having uniform thickness on the surface of the LED die  103 . 
       FIG. 2  illustrates a LED package  200  packaged by the aforementioned conformal distribution method. The advantage of using the conformal distribution method to coat the phosphor  101  is that the conformal distribution structure can convert the blue excitation light of the phosphor  101  into white light with great uniformity. Thus, this excellent color controlling ability may benefit the performance of the LED package  200 . 
     However, the manufacturing cost of the electrophoresis coating technique is too high to satisfy the demand of reducing the selling price of the LED package  200 . Moreover, because the phosphor  101  of the conformal structure may directly congregate on the surface of the LED die  103 , the light absorption of the phosphor  101  per unit area is low. In addition, since the phosphor  101  is separated far away from the light emitting surface of the LED package  200 , the excitation light of yellow or green phosphor may be easily absorbed by the red phosphor before emitting out of the light emitting surface, such that the light extraction efficiency of LED package  200  may be reduced. 
     To improve the light extraction efficiency of a LED package, a remote phosphor configuration technique is currently employed to coat the phosphor  101 .  FIG. 3  illustrates a LED package  300  packaged by the remote phosphor configuration technique in accordance with the prior art. The remote phosphor configuration technique includes coating a phosphor layer  301  on the molded molding compound  102  of the LED package  300 . Thus, the phosphor layer  301  is separated away from the LED die  103  for a spatial separation rather than being directly in contact with the LED die  103 . Accordingly, this spatial separation can reduce the re-absorption phenomenon of the emitted light of the LED die  103  and avoid the degradation of the phosphor  301  resulting from the high temperature of the LED die  103 , such that the light extraction efficiency and reliability of the LED package  300  can be significantly improved. 
     Besides, to improve the luminous flux of the LED package  300 , a lens  310  is usually assembled on to the packaged LED package. However, the process for fabricating this structure which includes packaging a LED die  103  by a molding compound  102 , forming a phosphor layer  301  on the surface of the molding compound  102 , and disposing the lens  310  on the phosphor layer  301 , may require two or more molding processes in the manufacturing process and make the manufacturing procedures more complex. Thus, it is difficult to reduce the manufacturing cost of the LED package  300 . 
     In view of the foregoing situations, it is desirous to provide an improved LED package and a method for manufacturing the same in order to simplify the manufacturing process and greatly reduce the manufacturing cost without deteriorating the light extraction efficiency and the reliability of the LED package. 
     SUMMARY OF THE INVENTION 
     One aspect of the invention is to provide a LED package, wherein the LED package includes a substrate, at least one LED die, a lens and a film. The LED die is arranged on the substrate, and has a top surface and a bottom surface. The lens is convexly formed on the substrate, and covers the LED die. The film has a uniform thickness, and has at least one phosphor layer disposed on the lens, a surface treatment layer disposed on the phosphor layer, an adhesive layer, which is devoid of any phosphor and having a first portion a second portion which has an upper surface and a lower surface, and a bending. The first portion is arranged between the lens and the phosphor layer. The second portion is extended to a position beyond the lens. The upper surface is lower than the top surface. The bottom surface and the lower surface are substantially positioned in the same elevation. The bending is located between the first portion and the second portion. 
     In another embodiment of the invention, the light-emitting diode package includes a substrate, at least one LED die, a film and a transparent molding compound. The substrate has a surface with a first part and a second part. The LED die is arranged on the first part. The film has a uniform thickness and includes a portion, a bending, a phosphor layer, and an adhesive. The phosphor has a first extending portion and includes a phosphor. The adhesive layer has a second extending portion, is devoid of any phosphor, and is closer to the substrate than the phosphor layer. The transparent molding compound is excluding the phosphor, is formed between the substrate and the portion, and covers the LED die. The first extending portion and the second extending portion extend along the surface. The second extending portion has an outer surface which is extended beyond and lower than the LED die. The bending is located between the transparent molding compound and the second part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above objects and advantages of the invention will become more readily apparent to those ordinarily skilled in the art after reviewing the following detailed description and accompanying drawings, in which: 
         FIG. 1  illustrates a LED package packaged by a traditional uniform distribution method; 
         FIG. 2  illustrates a schematic view of a LED package packaged by a conformal distribution phosphor method in accordance with the prior art. 
         FIG. 3  illustrates a LED package packaged by a remote phosphor configuration technique in accordance with the prior art. 
         FIGS. 4A to 4F  illustrate cross sectional views of the processing structures for manufacturing a LED package in accordance with one embodiment of the invention; and 
         FIG. 4G  illustrates an enlarged cross sectional view of the LED package structure shown in  FIG. 4F . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     The invention will now be described more specifically with reference to the following embodiments. It is to be noted that the following descriptions of preferred embodiments of this invention are presented herein for purpose of illustration and description only. It is not intended to be exhaustive or to be limited to the precise form disclosed. 
     The invention provides a LED package and a method for manufacturing the same.  FIGS. 4A to 4F  illustrate cross sectional views of the processing structures for manufacturing a LED package  400  in accordance with one embodiment of the invention. The method comprises steps as follows. As shown in  FIG. 4A , a substrate  404  is firstly provided wherein more than one LED dies  403  are fixed onto the substrate  404 . 
     Also, a flexible in-mold decoration film  40  comprising a phosphor layer  401  and a surface treatment layer  406  is provided. In the embodiment, the in-mold decoration film  40  further comprises a carrier layer  408 , a releasing film  407  and an adhesive layer  405 , wherein the releasing film  407  is disposed on the carrier layer  408 , the surfaced treated layer  406  is disposed on the releasing film, the phosphor layer  401  is disposed on the surface treatment layer  406 , and an adhesive layer  405  is disposed on the phosphor layer  401 (shown in  FIG. 4B ). It should be appreciated that the adhesive layer  405  of the in-mold decoration film  40  is optional, so that in some embodiments of the invention, the in-mold decoration film  40  may not comprise any adhesive layer. 
     The carrier layer  408  can be a flexible plastic substrate, e.g. a substrate consisting of polyethylene terephthalate (PET) or other polymeric materials with the likely characteristics. The releasing film  407  preferably consists of polysiloxane. While the releasing film  407  is subjected to stress, heat or light, the carrier layer  408  can be separated from the in-mold decoration film  40 . The surface treatment layer  406  possesses the characteristics of being scratchproof, waterproof, and moisture proof. In some embodiments, the surface treatment layer  406  can be a silicone gel layer or an epoxy resin layer. The phosphor layer  401  preferably is formed by steps of mixing phosphor and adhesive and then coating the mixture onto the carrier layer  408 . In some embodiments, the phosphor layer  401  is a thin visible-light excitation layer printed or coated on the carrier layer  408 . 
     Subsequently, the in-mold decoration film  40  is deformed to define a plurality of recesses  411  using the surface treatment layer  406  serves as an outer wall of the recesses  411 . In some embodiments, the deformation of the in-mold decoration film  40  comprises stamping the in-mold decoration film  40  with a stamping die  409 . In the embodiment, the in-mold decoration film  40  is deformed by a vacuum lamination process to make the in-mold decoration film  40  conform to the stamping die  409  (as shown in  FIG. 4C ). In an embodiment, the stamping die  409  has a plurality of recesses, each of which has a cambered surface. Thus, each of the recesses  411  defined on the deformed in-mold decoration film  40  and conforming to the stamping die  409  has a concave cambered surface. 
     Next, the recesses  411  are filled with a transparent molding compound  402  (as shown in  FIG. 4D ). In some embodiments of the invention, the transparent molding compound  402  consists of melted epoxy resin. However, the high operating temperature of LED die  409  may trigger the epoxy resin undergoing deterioration, such as yellowing, so as to lead the emitted light of the LED package  400  attenuated. Therefore, in some preferred embodiments, melted epoxy resin can be substituted with silicone gel, which possesses characteristics of high reflectivity, heat-resistance, good insulation, chemical stability, high light transmittance (for the light in the wavelength range from 300 to 700 nm), and high reliability, and serves as the transparent molding compound  402 . 
     Thereafter, the substrate  404  and the in-mold decoration film  40  are assembled to make each of the LED dies  403  disposed in one of the recesses  411  and encapsulated in the transparent molding compound  402  (as shown in  FIG. 4E ). In the embodiment, to assemble the substrate  404  and the in-mold decoration film  40 , the substrate  404  having the LED dies  403  fixed thereon is sucked by a tool  41  (as shown in  FIG. 4D ), and then is pressed onto the deformed in-mold decoration film  40  which is carried by the stamping die  409  and contains the transparent molding compound  402 . In some embodiments, each of the LED dies  403  corresponds to one of the recesses, thus each recess may be allocated one or more LED dies  403  according to the design of the LED package  400 . 
     After the transparent molding compound  402  is cured to form a lens  410 , the assembled substrate  404  and the in-mold decoration film  40  are then released from the stamping die  409 , and the carrier layer  408  is separated from the in-mold decoration film  40  by stress, heat or light to form a plurality of LED packages  400  as shown in  FIG. 4F . 
       FIG. 4G  illustrates an enlarged cross sectional view of the LED package  400  structure shown in  FIG. 4F . Referring to  FIG. 4F , the LED package  400  comprises a substrate  404  having at least one LED die  403  fixed thereon; a lens  410  consisting of cured transparent molding compound  402  molded on the substrate  404  in order to encapsulate the LED die  403 ; and an in-mold decoration film  40  comprising a phosphor layer  401  disposed on the lens  410 ; and a surface treatment layer  406  disposed on the phosphor layer  401 . 
     In the preferable embodiment, the surface treatment layer  406  is a silicone gel layer. The phosphor layer  401  is a thin phosphor coating layer. Additionally, in another embodiment, an optional adhesive layer  405  can be disposed between the phosphor layer  401  and the lens  410 . The transparent molding compound  402  which is cured to form the lens  410  can be silicone gel. 
     In accordance with the aforementioned embodiments, a LED package and a method for manufacturing the same are provided. In the embodiments, an in-mold decoration film having a phosphor layer and a surface treatment layer is utilized as an outer film to package a LED die, wherein the surface treatment layer is deformed to identify at least one recess using the surface treatment layer serves as an outer wall of the recess; and the recess is then filled with a transparent molding compound which can be cured to form a lens after the substrate is assembled with the in-mold decoration film to dispose the LED die in the recess, thereby the LED die fixed on the substrate can be capsulated in the lens by merely one single molding process. 
     In other words, an improved optical performance similar to that provided by a conventional LED package having a remote phosphor configuration structure can be accomplished by the embodiments of the invention. Nevertheless, merely one molding process is required. Besides, a lens structure which can improve the light flux of the LED package is also provided by the same approach. Therefore, while maintaining the light extraction efficiency and the reliability of the conventional LED package, the embodiments not only can simplify the traditional LED packaging process but also can reduce the manufacturing cost significantly. 
     While the invention has been described in terms of what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention needs not be limited to the disclosed embodiment. On the contrary, it is intended to cover various modifications and similar arrangements included within the spirit and scope of the appended claims which are to be accorded with the broadest interpretation so as to encompass all such modifications and similar structures.