Abstract:
A method of fabricating a semiconductor package is provided, including: providing a heat dissipating structure having a heat dissipating portion, a deformable supporting portion coupled to the heat dissipating portion, and a coupling portion coupled to the supporting portion; coupling a carrier having a semiconductor element carried thereon to the coupling portion of the heat dissipating structure to form between the carrier and the heat dissipating portion a receiving space for the semiconductor element to be received therein; and forming in the receiving space an encapsulant that encapsulates the semiconductor element. The use of the supporting portion enhances the bonding between the heat dissipating structure and a mold used for packaging, thereby preventing the heat dissipating structure from having an overflow of encapsulant onto an external surface of the heat-dissipating portion.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application claims under 35 U.S.C. §119(a) the benefit of Taiwanese Application No. 101142158, filed Nov. 13, 2012, the entire contents of which is incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to methods of fabricating a semiconductor package, and, more particularly, to a method of fabricating a semiconductor package having a heat dissipating structure. 
     2. Description of Related Art 
     A modern electronic product is compact-sized and low-profiled. With the rapid development of a semiconductor fabrication process, more and more electrical elements are allowed to be integrated into a chip. However, the electronic elements, when in operation, generate a great amount of heat, and the heat cannot be dissipated to a region outside of the chip because the encapsulant does not have well enough heat dissipating quality. Accordingly, the lifespan of the electronic elements is reduced. Therefore, how to dissipate the heat generated by the electronic elements effectively is an important issue in the art. In general, a heat dissipation is disposed above the chip to dissipating the heat generated by the chip to an ambient environment. 
     According to the prior art, a compression molding method is used during a packaging process, to disposed a heat dissipation on a chip, as shown in  FIGS. 1A to 1D , which illustrate a method of fabricating a semiconductor package  1  according to the prior art. 
     As shown in  FIG. 1A , a heat dissipation  11  is disposed on a side in a mold  10 , and in physical contact with a surface of the mold  10 . 
     As shown in  FIG. 1B , a substrate  12  having a plurality of semiconductor elements  12  disposed thereon is disposed on another side in the mold  10  (i.e., an upper portion  101 ), and the semiconductor elements  121  are disposed between the substrate  12  and the heat dissipations  11 . The semiconductor element  121  is electrically connected via a plurality of bonding wires  120  to the substrate  12 . 
     As shown in  FIG. 1C , an encapsulant  13  is then formed in a mold cavity  100  of the mold  10  to encapsulate the semiconductor element  121 . 
     As shown in  FIG. 1D , a singulation process (along a cutting path S) are performed after the encapsulant  13  is released from the mold  10 , to form a plurality of semiconductor packages  1 . 
     In the method according to the prior art, the heat dissipations  11  are not closely adhered to the mold  10 . Accordingly, during the formation of the encapsulant  13 , the encapsulant  13  will flow via a side of the heat dissipation  11  to an external surface of the heat dissipation  11  due to a capillarity phenomenon. In other words, a resin bleed phenomenon happens. After the encapsulant  13  is released from the mold  10 , a residual encapsulant  13 ′ still stays on the external surface of the heat dissipations  11 , as shown in  FIG. 1  D′, and a semiconductor package  1 ′ of poor quality is formed. 
     Therefore, how to overcome the problems of the prior art is becoming an urgent issue in the art. 
     SUMMARY OF THE INVENTION 
     In view of the problems of the prior art, the present invention provides a method of fabricating a semiconductor package, comprising: providing a heat dissipating structure having a heat dissipating portion, a deformable supporting portion coupled to the heat dissipating portion, and a coupling portion coupled to the supporting portion; coupling a carrier having a semiconductor element carried thereon to the coupling portion of the heat dissipating structure to form between the carrier and the heat dissipating portion a receiving space for the semiconductor element to be received therein; and forming in the receiving space an encapsulant that encapsulates the semiconductor element. 
     In an embodiment, the method further comprises, after forming the encapsulant, removing the coupling portion and the supporting portion. 
     In an embodiment, the heat dissipating portion has a groove. 
     In an embodiment, the heat dissipating portion is less than or equal to the coupling portion in size. 
     In an embodiment, the encapsulant is formed in a mold, and the mold has a clamping portion that clamps the carrier and the coupling portion and a mold cavity less than the heat dissipating structure in height. 
     In an embodiment, the mold has a plurality of perforations that absorb the heat dissipating portion of the heat dissipating structure by vacuum-pumping when the encapsulant is formed. 
     In an embodiment, the coupling portion has a first positioning portion, and the carrier has a second positioning portion corresponding to the first positioning portion. 
     In a method of fabricating a semiconductor package according to the present invention, the use of the supporting portion that is deformable enhances the bonding between the heat dissipating portion and a mold used for packaging, thereby preventing the heat dissipating structure from having an overflow of encapsulant onto an external surface of the heat-dissipating portion when the encapsulant is formed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       The invention can be more fully understood by reading the following detailed description of the preferred embodiments, with reference made to the accompanying drawings, wherein: 
         FIGS. 1A-1D  are cross-sectional diagrams illustrating a method of fabricating a semiconductor package according to the prior art, wherein FIG.  1 D′ is an actual state of  FIG. 1D ; 
         FIGS. 2A-2E  are cross-sectional diagrams illustrating a method of fabricating a semiconductor package according to the present invention, wherein FIG.  2 A′ is a top view of  FIG. 2A , FIG.  2 A″ is another embodiment of  FIG. 2A , FIG.  2 B′ is another embodiment of  FIG. 2B , and FIG.  2 C′ is another embodiment of  FIG. 2C ; and 
         FIG. 3  is a cross-section diagram illustrating another embodiment of  FIG. 2C . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following illustrative embodiments are provided to illustrate the disclosure of the present invention, these and other advantages and effects can be apparently understood by those in the art after reading the disclosure of this specification. The present invention can also be performed or applied by other different embodiments. The details of the specification may be on the basis of different points and applications, and numerous modifications and variations can be devised without departing from the spirit of the present invention. 
       FIGS. 2A-2E  are cross-sectional diagrams illustrating a method of fabricating a semiconductor package  2  according to the present invention. 
     As shown in FIGS.  2 A and  2 A′, wherein FIG.  2 A′ is a top view of  FIG. 2A , an integrated heat dissipating structure  21  is provided that has a heat dissipating portion  211 , a plurality of supporting portions  212  coupled to the heat dissipating portion  211 , and a coupling portion  213  coupled to the supporting portions  212 . 
     In an embodiment, the heat dissipating portion  211  has a groove  211   a  formed on an upper side thereof and surrounding a periphery of the heat dissipating portion  211 , the heat dissipating structure  21  has four supporting portions  212 , and the coupling portion  213  is a ring-shaped and has a first positioning portion  2130  (e.g., a positioning hole or other structures). In another embodiment, the heat dissipating structure  21  has the heat dissipating portion  211 , the supporting portions  212  and the coupling portion  213 , which are assembled individually. In other words, the heat dissipating structure  21  is not integrated. The heat dissipating structure  21  may have more supporting portions  212 . 
     In an embodiment, the size A (e.g., length and width) of the heat dissipating portion  211  is less than the size B (e.g., length and width) of an outer structure of the coupling portion  213 , as shown in FIG.  2 A′. In another embodiment, the size A of the heat dissipating portion  211  is equal to the size B′ of the outer structure of the coupling portion  213 , as shown in  FIG. 3 . 
     In an embodiment, the supporting portions  212  are deformable, and have their shapes or structures changed when an external force is applied to the heat dissipating structure  21 . In an embodiment, the supporting portions  212  are made of any deformable material. In an embodiment, the supporting portions  212  have a flexible, bendable buffer structure. In the heat dissipating structure  21 ′ shown in FIG.  2 A″, the supporting portions  212 ′ have a structure in the shape of a spiral, wave or the letter “S.” 
     In an embodiment, the heat dissipating structure  21  defines a height L from the heat dissipating portion  211  to the coupling portion  213 . 
     As shown in  FIG. 2B , which shows a fabrication process subsequent to  FIG. 2A , the coupling portion  213  of the heat dissipating structure  21  is attached to the carrier  22  via a resin material (not shown), a receiving space  20  is formed between the carrier  22  and the heat dissipating portion  211 , and the carrier  22  has a plurality of semiconductor elements  221  disposed thereon and disposed in the receiving space  20 . 
     In an embodiment, the carrier  22  is a lead frame. In another embodiment, the carrier  22  is a packaging substrate. 
     In an embodiment, each of the semiconductor elements  221  is electrically connected to the carrier  22  via a plurality of bonding wires  220 . In another embodiment, the semiconductor elements  221  are electrically connected to the carrier  22  via conductive bumps in a flip-chip manner, for example. 
     In an embodiment, the carrier  22  has a second positioning portion  222  (e.g., a positioning hole or other structures) disposed on a periphery thereof and corresponding to the first positioning portion  2130 . The carrier  22  can be aligned with and secured to the heat dissipating structure  222  by using the first positioning portion  2130  and the second positioning portion  222 . 
     In an embodiment, as shown in FIG.  2 B′, a pre-molding  23   a  is formed on a bottom side of the carrier  22  before a packaging process is performed. 
     As shown in  FIG. 2C , which shows a fabrication process subsequent to  FIG. 2B , the heat dissipating structure  21  and the carrier  22  are placed in a mold  30 . 
     In an embodiment, the mold  30  has an upper mold  301  and a lower mold  302 , and the upper mold  301  and the lower mold  302  constitute a mold cavity  30   a  for a packaging material to be filled therein. When the mold  30  is closed, the height H of the mold cavity  30   a  is less than the height L defined by the heat dissipating structure  21 . Since the supporting portions  212  are deformable and the supporting portions  212  are pressed by the upper mold  301  to deform when the upper mold  301  and the lower mold  302  is closed, the heat dissipating structure  21  and the carrier  22  can be placed in the mold  30 . Besides, since the upper mold  301  presses downward to the heat dissipating portion  211 , the heat dissipating portion  211  is coupled to upper mold  301  securely. 
     In an embodiment, the upper mold  301  has a clamping portion  300  that clamps left and right sides of the carrier  22  and the coupling portion  213 . In specific, the height H of the mold cavity  30   a  is a distance between the clamping portion  300  and the lower surface of the upper mold  301 . 
     In an embodiment, the upper mold  301  has a third positioning portion  303  (e.g., a pillar or other structures) corresponding to the first positioning portion  2130  and the second positioning portion  222 . Therefore, the third positioning portion  303  can be coupled and locked to the first positioning portion  2130  and the second positioning portion  222 , and the heat dissipating structure  21  and the carrier  22  can be placed in the mold cavity  30   a  accurately. 
     In an embodiment, as shown in FIG.  2 C′, a plurality of perforations  310  are formed on the upper mold  301 ′, and absorb the heat dissipating portion  211  of the heat dissipating structure  21  by vacuum-pumping the mold  30 ′ after the upper mold  301 ′ is pressed to the lower mold  302 . Therefore, the sealing between the heat dissipating portion  211  and the upper mold  301  is enhanced. 
     As shown in  FIG. 2D , which shows a fabrication process subsequent to  FIG. 2C , an encapsulant  23  is filled in the mold cavity  30   a  and the receiving space  20  and encapsulates the semiconductor element  221 . 
     In another embodiment, as shown in FIG.  2 C′, when the encapsulant  23  is forming, the perforations  310  absorb the heat dissipating portion  211  by vacuum pumping. 
     In a method of fabricating a semiconductor package according to the present invention, the deformable supporting portions  212  allow the heat dissipating portion  211  to be tightly sealed to the upper mold  301 , and no space is thus formed between the heat dissipating portion  211  and the upper mold  301 . Accordingly, when the encapsulant  23  is formed, the encapsulant  23  will not flow to an external surface of the heat dissipating portion  211 , thereby preventing a bleeding of encapsulant from occurring. 
     In an embodiment, even though flowing to a side surface of the heat dissipating portion  211 , the encapsulant  13  will not continue to flow to the external surface of the heat dissipations  11 . 
     In an embodiment, since the mold  30  is vacuum inside, the sealing between the heat dissipating portion  211  and the upper mold  301  is enhanced, which further prevents the bleeding of encapsulant from occurring. 
     As shown in  FIG. 2E , the mold  30  is removed, a singulation process is performed to fabricate a plurality of semiconductor packages  2 , and the coupling portion  213  and the supporting portions  212  are removed. 
     In an embodiment, if the encapsulant  23  is going to flow to the external surface of the heat dissipating portion  211  for some reasons, the groove  211   a  limits the encapsulant to stay therein, not to flow further. During the singulation process, the groove  211   a  and the resin material formed therein can be removed. Therefore, no residual encapsulant  23  will stay on the heat dissipating portion  211  of the semiconductor package  2 . Accordingly, the groove  211   a  can be the edge of the cutting path, for the cutting process to be performed smoothly. 
     In a method of fabricating a semiconductor package according to the present invention, the use of the supporting portions of the heat dissipating structure enhances the sealing between the heat dissipating portion and the mold and solves the problem that the encapsulant bleeds during the fabrication process. 
     Besides, the supporting portions can change the height of the semiconductor package before packaged according to the space of the mold. Therefore, the method of fabricating a semiconductor package according to the present invention can be applied to a variety of packaging machines. 
     The foregoing descriptions of the detailed embodiments are only illustrated to disclose the features and functions of the present invention and not restrictive of the scope of the present invention. It should be understood to those in the art that all modifications and variations according to the spirit and principle in the disclosure of the present invention should fall within the scope of the appended claims.