Patent Publication Number: US-2012037937-A1

Title: Led package structure and method of making the same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The instant disclosure relates to an LED package structure and a method of making the same, and more particularly, to an LED package structure for increasing heat-dissipating efficiency and a method of making the same. 
     2. Description of Related Art 
     The invention of the lamp greatly changed the style of building construction and the living style of human beings, allowing people to work during the night. Traditional lighting devices such as lamps that adopt incandescent bulbs, fluorescent bulbs, or power-saving bulbs have been generally well-developed and used intensively for indoor illumination. 
     However, these traditional lamps have the disadvantages of quick attenuation, high power consumption, high heat generation, short working life, high fragility, and being not recyclable when compared to the newly developed light-emitting diode (LED) devices. Thus, these traditional light bulbs are gradually phased out in favor of the new and more efficient high-powered LED devices. 
     SUMMARY OF THE INVENTION 
     One particular aspect of the instant disclosure is to provide an LED package structure for increasing heat-dissipating efficiency. 
     Another particular aspect of the instant disclosure is to provide a method of making an LED package structure for increasing heat-dissipating efficiency. 
     To achieve the above-mentioned advantages, one embodiment of the instant disclosure provides an LED package structure, including: a substrate unit, a conductive unit, a heat-dissipating unit, a light-emitting unit and a package unit. The substrate unit includes at least one insulating substrate. The conductive unit includes at least two plate-shaped top conductive pads disposed on the top surface of the insulating substrate, at least two plate-shaped bottom conductive pads disposed on the bottom surface of the insulating substrate, and a plurality of penetrating conductive posts passing through the insulating substrate. The two top conducive pads are respectively electrically connected to the two bottom conductive pads through the penetrating conductive posts. The heat-dissipating unit includes at least one plate-shaped top heat-dissipating block disposed on the top surface of the insulating substrate and at least one plate-shaped bottom heat-dissipating block disposed on the bottom surface of the insulating substrate. The light-emitting unit includes at least one light-emitting element disposed on the top heat-dissipating block and electrically connected between the two top conductive pads. The package unit includes a package resin disposed on the conductive unit and the heat-dissipating unit to cover the light-emitting element. 
     To achieve the above-mentioned advantages, one embodiment of the instant disclosure provides a method of making an LED package structure, including the steps of: (a) providing a substrate module including a substrate unit, a conductive unit and a heat-dissipating unit; wherein the substrate unit includes at least one insulating substrate, the conductive unit includes at least two top conductive pads disposed on the top surface of the insulating substrate, at least two bottom conductive pads disposed on the bottom surface of the insulating substrate and a plurality of penetrating conductive posts passing through the insulating substrate, the two top conducive pads are respectively electrically connected to the two bottom conductive pads through the penetrating conductive posts, and the heat-dissipating unit includes at least one top heat-dissipating block disposed on the top surface of the insulating substrate and at least one bottom heat-dissipating block disposed on the bottom surface of the insulating substrate; (b) attaching at least one light-emitting element to the top heat-dissipating block through die-attaching glue; (c) solidifying the die-attaching glue to position the light-emitting element on the top heat-dissipating block; (d) cleaning the outer surface of the light-emitting element and the outer surface of the two top conductive pads by plasma; (e) electrically connecting the light-emitting element between the two top conductive pads; and then (f) forming a package resin to cover the light-emitting element. 
     Therefore, heat generated by the light-emitting element can be transmitted to external world through the top heat-dissipating block, the insulating substrate (or the penetrating heat-dissipating layers) and the bottom heat-dissipating block in sequence. In other words, the heat generated by the light-emitting element can be quickly transmitted from the top heat-dissipating block to the bottom heat-dissipating block through the insulating substrate or the penetrating heat-dissipating layers, thus the heat-dissipating efficiency of the instant disclosure can be increased effectively. 
     To further understand the techniques, means and effects the instant disclosure takes for achieving the prescribed objectives, the following detailed descriptions and appended drawings are hereby referred, such that, through which, the purposes, features and aspects of the instant disclosure can be thoroughly and concretely appreciated. However, the appended drawings are provided solely for reference and illustration, without any intention that they be used for limiting the instant disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1-1  and  1 - 2  shows a flow chart of the method for making an LED package structure according to the first, the fourth and the fifth embodiments; 
         FIG. 1A  shows one perspective, schematic view of the substrate module of the LED package structure according to the first embodiment of the instant disclosure; 
         FIG. 1B  shows one lateral, schematic view of the substrate module of the LED package structure according to the first embodiment of the instant disclosure; 
         FIG. 1C  shows one perspective, schematic view of the light-emitting element electrically connected to the substrate module of the LED package structure according to the first embodiment of the instant disclosure; 
         FIG. 1D  shows one perspective, schematic view of the LED package structure according to the first embodiment of the instant disclosure; 
         FIG. 1E  shows one lateral, schematic view of the LED package structure according to the first embodiment of the instant disclosure; 
         FIG. 2  shows one lateral, schematic view of the LED package structure according to the second embodiment of the instant disclosure; 
         FIG. 3  shows one lateral, schematic view of the LED package structure according to the third embodiment of the instant disclosure; 
         FIG. 4  shows one lateral, schematic view of the LED package structure according to the fourth embodiment of the instant disclosure; 
         FIG. 5  shows one lateral, schematic view of the LED package structure according to the fifth embodiment of the instant disclosure; and 
         FIG. 6  shows one lateral, schematic view of the LED package structure according to the sixth embodiment of the instant disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to  FIGS. 1-1 ,  1 - 2  and  1 A- 1 E, the first embodiment of the instant disclosure provides a method of making an LED package structure for increasing heat-dissipating efficiency, comprising the steps of: 
     The step S 100  is that: referring to  FIGS. 1-1 ,  1 - 2 ,  1 A and  1 B ( FIG. 1B  shows a lateral view of  FIG. 1A ), providing a substrate module M including a substrate unit  1 , a conductive unit  2  and a heat-dissipating unit  3 ; wherein the substrate unit  1  includes at least one insulating substrate  10 , the conductive unit  2  includes at least two top conductive pads  21  disposed on the top surface of the insulating substrate  10 , at least two bottom conductive pads  22  disposed on the bottom surface of the insulating substrate  10  and a plurality of penetrating conductive posts  23  passing through the insulating substrate  10 , the two top conducive pads  21  are respectively electrically connected to the two bottom conductive pads  22  through the penetrating conductive posts  23 , and the heat-dissipating unit  3  includes at least one top heat-dissipating block  31  disposed on the top surface of the insulating substrate  10  and at least one bottom heat-dissipating block  32  disposed on the bottom surface of the insulating substrate  10 . In addition, the substrate unit  1  includes a plurality of conductive through holes  101  passing through the insulating substrate  10 , and the penetrating conductive posts  23  are respectively filled in the conductive through holes  101 . 
     The step S 102  is that: referring to  FIGS. 1-1 ,  1 - 2  and  1 C, attaching at least one light-emitting element  40  to the top heat-dissipating block  31  through die-attaching glue (or die-attaching piece) H. For example, the light-emitting element  40  may be an LED chip. In addition, the method further comprises S 101  that is sequentially washing and baking the substrate module M and the light-emitting element  40  before the step of S 102  (washing the substrate module M and the light-emitting element  40 , and then baking the substrate module M and the light-emitting element  40 ), and the temperature for the baking process may be between about 80-120° C. 
     The step S 104  is that: referring to  FIGS. 1-1 ,  1 - 2  and  1 C, solidifying the die-attaching glue H to position the light-emitting element  40  on the top heat-dissipating block  31 . For example, the temperature for the solidifying process may be between about 80-180° C., and the die-attaching glue H may be a conductive or non-conductive material, such as polymeric material, metal material or combing polymeric material and metal material. 
     The step S 106  is that: referring to  FIGS. 1-1 ,  1 - 2  and  1 C, cleaning the outer surface of the light-emitting element  40  and the outer surface of the two top conductive pads  21  by plasma. For example, the power and the time for the plasma cleaning process may be 500 mW and between about 3-15 minutes, respectively. 
     The step S 108  is that: referring to  FIGS. 1-1 ,  1 - 2  and  1 C, electrically connecting the light-emitting element  40  between the two top conductive pads  21 . For example, the temperature and the bonding pressure for the electrically connecting process may be between about 100-230° C. and between about 10-150 gram, respectively. In addition, the positive electrode and the negative electrode of the light-emitting element  40  can respectively electrically connected to the two top conductive pads  21  through two conductive wires W. The method further comprising S 109  that is pre-curing the substrate module M and the light-emitting element  40  to remove redundant moisture and increase the temperature for the electrically connecting process after the step of S 108 . 
     The step S 110  is that: referring to  FIGS. 1-1 ,  1 - 2 ,  1 D and  1 E ( FIG. 1E  shows a lateral view of  FIG. 1D ), forming a package resin  50  to cover the light-emitting element  40  to finish the manufacture of the LED package structure for increasing heat-dissipating efficiency of the instant disclosure. For example, the package resin  50  can be a light-permitting lens made of silicone or epoxy. In addition, the package resin  50  can be formed on the substrate module M (including the substrate unit  1 , the conductive unit  2  and heat-dissipating unit  3 ) through a mold by molding method, and the temperature for the molding process is between about 50-180° C. 
     Moreover, the method may further comprise sawing, testing and sorting, and taping in sequence. For example, many LED package structures can be manufactured at the same time, and the LED package structures can be cut to form many strip LED package structures by sawing process. In addition, every strip LED package structure needs to be tested and sorted (GO or NG) by testing and sorting process, and then every normal strip LED package structure is rolled up by taping process. 
     Hence, referring to  FIGS. 1D and 1E , the first embodiment of the instant disclosure provides an LED package structure for increasing heat-dissipating efficiency, including: a substrate unit  1 , a conductive unit  2 , a heat-dissipating unit  3 , a light-emitting unit  4  and a package unit  5 . 
     The substrate unit  1  includes at least one insulating substrate  10 , and the insulating substrate  10  can be made of any type of insulating material. For example, the insulating substrate  10  may be is a ceramic substrate that has 92˜98% Al 2 O 3  and has been sintered. 
     The conductive unit  2  can be made of silver material. The conductive unit  2  includes at least two plate-shaped top conductive pads  21  (it means flat conductive pad) disposed on the top surface of the insulating substrate  10 , at least two plate-shaped bottom conductive pads  22  (it means flat conductive pad) disposed on the bottom surface of the insulating substrate  10 , and a plurality of penetrating conductive posts  23  passing through the insulating substrate  10 . The two top conducive pads  21  are respectively electrically connected to the two bottom conductive pads  22  through the penetrating conductive posts  23 . For example, the substrate unit  1  includes a plurality of conductive through holes  101  passing through the insulating substrate  10 , and the penetrating conductive posts  23  are respectively filled in the conductive through holes  101 . In addition, the two top conductive pads  21  and the two bottom conductive pads  22  are substantially symmetrically disposed on two opposite surfaces of the insulating substrate  10 . 
     The heat-dissipating unit  3  includes at least one plate-shaped top heat-dissipating block  31  (it means flat heat-dissipating pad) disposed on the top surface of the insulating substrate  10  and at least one plate-shaped bottom heat-dissipating block  32  (it means flat heat-dissipating pad) disposed on the bottom surface of the insulating substrate  10 . For example, the top heat-dissipating block  31  is positioned between the two top conducive pads  21  and the bottom heat-dissipating block  32  is positioned between the two bottom conductive pads  22 , and the top heat-dissipating block  31  and the bottom heat-dissipating block  32  are substantially symmetrically disposed on two opposite surfaces of the insulating substrate  10 . 
     The light-emitting unit  4  includes at least one light-emitting element  40  disposed on the top heat-dissipating block  31  and electrically connected between the two top conductive pads  21 . For example, the light-emitting element  40  may be an LED chip attached to the top heat-dissipating block  31  through die-attaching glue H or die-attaching piece. The positive electrode and the negative electrode of the light-emitting element  40  can respectively electrically connected to the two top conductive pads  21  through two conductive wires W. Therefore, heat generated by the light-emitting element  40  can be transmitted to external world through the top heat-dissipating block  31 , the insulating substrate  10  and the bottom heat-dissipating block  32  in sequence. In other words, the heat generated by the light-emitting element  40  can be transmitted from the top heat-dissipating block  31  to the bottom heat-dissipating block  32 , thus the heat-dissipating efficiency of the instant disclosure can be increased effectively. 
     The package unit  5  includes a package resin  50  disposed on the conductive unit  2  and the heat-dissipating unit  3  to cover the light-emitting element  40 . In other words, when the top surface of the insulating substrate  10  is covered with the package resin  50 , the conductive unit  2 , the heat-dissipating unit  3  and the light-emitting unit  4  are covered with the package resin  50  at the same time. For example, the package resin  50  can be a light-permitting lens made of silicone or epoxy. 
     Referring to  FIG. 2 , the second embodiment of the instant disclosure provides an LED package structure for increasing heat-dissipating efficiency, including: a substrate unit  1 , a conductive unit  2 , a heat-dissipating unit  3 , a light-emitting unit  4  and a package unit  5 . Comparing  FIG. 2  with  FIG. 1E , the difference between the second embodiment and the first embodiment is that: in the second embodiment, the heat-dissipating unit  3  includes a plurality of penetrating heat-dissipating layers  33  passing through the insulating substrate  10  and connected between the top heat-dissipating block  31  and the bottom heat-dissipating block  32 . In addition, the substrate unit  10  includes a plurality of heat-dissipating through holes  102  passing through the insulating substrate  10 , and the penetrating heat-dissipating layers  33  are respectively filled in the heat-dissipating through holes  102 . 
     Therefore, heat generated by the light-emitting element  40  can be transmitted to external world through the top heat-dissipating block  31 , the penetrating heat-dissipating layers  33  (of course including the insulating substrate  10 ) and the bottom heat-dissipating block  32  in sequence. In other words, the heat generated by the light-emitting element  40  can be quickly transmitted from the top heat-dissipating block  31  to the bottom heat-dissipating block  32  through the penetrating heat-dissipating layers  33 , thus the heat-dissipating efficiency of the instant disclosure can be increased effectively. 
     Referring to  FIG. 3 , the third embodiment of the instant disclosure provides an LED package structure for increasing heat-dissipating efficiency, including: a substrate unit  1 , a conductive unit  2 , a heat-dissipating unit  3 , a light-emitting unit  4  and a package unit  5 . Comparing  FIG. 3  with  FIG. 1E , the difference between the third embodiment and the first embodiment is that: in the third embodiment, the package resin  50  may be a light-permitting lens made mixed by light-permitting resin  501  with phosphor powders  502 . For example, the package resin  50  may be a light-permitting lens made mixed by phosphor powders  502  with silicone or epoxy. 
     Referring to  FIG. 4 , the fourth embodiment of the instant disclosure provides an LED package structure for increasing heat-dissipating efficiency, including: a substrate unit  1 , a conductive unit  2 , a heat-dissipating unit  3 , a light-emitting unit  4  and a package unit  5 . Comparing  FIG. 4  with  FIG. 3 , the difference between the fourth embodiment and the third embodiment is that: in the fourth embodiment, the phosphor powders  502  are deposited and concentrated on the outer surface of the light-emitting element  4  by centrifugal force or deposition method as shown in  FIG. 4 . 
     Referring to  FIG. 5 , the fifth embodiment of the instant disclosure provides an LED package structure for increasing heat-dissipating efficiency, including: a substrate unit  1 , a conductive unit  2 , a heat-dissipating unit  3 , a light-emitting unit  4  and a package unit  5 . Comparing  FIG. 5  with  FIG. 1E , the difference between the fifth embodiment and the first embodiment is that: the fifth embodiment further comprises a phosphor unit  6  that includes a phosphor layer  60  covering the light-emitting element  40 , and the phosphor layer  60  includes a plurality of phosphor powders  600  mixed therein and close to the light-emitting element  40 . In other words, the phosphor powders  600  can be deposited and concentrated to cover the top surface of the light-emitting element  4 , thus light generated by the light-emitting element  40  can pass through the phosphor unit  6  to obtain perfect spectrum conversion. 
     Referring to  FIGS. 1-1 ,  1 - 2  and  5 , the fifth embodiment provides a method for making the LED package structure. Before the step of S 110 , the method of the fifth embodiment comprises: forming a phosphor layer  60  mixed with phosphor powders  600  to cover the light-emitting element  40  (S 200 ) by adhesive dripping or spraying; depositing and concentrating the phosphor powders  600  on the light-emitting element  40  by centrifugal force (S 202 ); and then solidifying the phosphor layer  60  for positioning the phosphor layer  60  on the light-emitting element  40  (S 204 ). In addition, the package resin  50  may be a light-permitting lens made of silicone or epoxy, and the phosphor layer  60  is covered by the package resin  50 . 
     Referring to  FIG. 6 , the sixth embodiment of the instant disclosure provides an LED package structure for increasing heat-dissipating efficiency, including: a substrate unit  1 , a conductive unit  2 , a heat-dissipating unit  3 , a light-emitting unit  4  and a package unit  5 . Comparing  FIG. 6  with  FIG. 1E , the difference between the sixth embodiment and the first embodiment is that: the sixth embodiment further comprises a frame unit  7  that includes an opaque annular frame  70  disposed on the insulating substrate  10  (or on a substrate module M composed of the substrate unit  1 , the conductive unit  2  and the heat-dissipating unit  3  as shown in  FIG. 1E ) and around an external peripheral surface of the package resin  50 . 
     Referring to  FIGS. 1-1 ,  1 - 2  and  6 , the sixth embodiment provides a method for making the LED package structure. Before the step of S 110 , the method of the sixth embodiment comprises: forming an opaque annular frame  70  on the insulating substrate  10  (or on a substrate module M composed of the substrate unit  1 , the conductive unit  2  and the heat-dissipating unit  3  as shown in  FIG. 1E ) (S 300 ). Hence, when the light-emitting element  40  is covered by the package resin  50 , the external peripheral surface of the package resin  50  can be covered by the opaque annular frame  70 . Therefore, the light generated by the light-emitting element  40  can be reflected through the inner surface of the opaque annular frame  70  to increase the light-emitting efficiency and the light-gathering capability of the instant disclosure. 
     In conclusion, heat generated by the light-emitting element can be transmitted to external world through the top heat-dissipating block, the insulating substrate (or the penetrating heat-dissipating layers) and the bottom heat-dissipating block in sequence. In other words, the heat generated by the light-emitting element can be quickly transmitted from the top heat-dissipating block to the bottom heat-dissipating block through the insulating substrate or the penetrating heat-dissipating layers, thus the heat-dissipating efficiency of the instant disclosure can be increased effectively. 
     The above-mentioned descriptions merely represent the preferred embodiments of the instant disclosure, without any intention or ability to limit the scope of the instant disclosure which is fully described only within the following claims. Various equivalent changes, alterations or modifications based on the claims of instant disclosure are all, consequently, viewed as being embraced by the scope of the instant disclosure.