Abstract:
The present invention relates to a stacked semiconductor package having flexible circuit board therein. The semiconductor package comprises a substrate and a chip assembly. The chip assembly comprises at least a first chip, a second chip and a flexible circuit board. The second chip is disposed above the first chip, and is electrically connected to the first chip by the flexible circuit board. The chip assembly is electrically connected to the substrate. As a result, the interposer of prior art is omitted, the overall thickness of the stacked semiconductor package of the present invention is reduced, and the manufacturing procedure is simplified.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a stacked semiconductor package. In particular, the present invention relates to a stacked semiconductor package having a flexible circuit board therein. 
     2. Description of the Prior Art 
     Please refer to  FIG. 1 , illustrating a cross-sectional view of a conventional stacked semiconductor package. The conventional stacked semiconductor package includes a substrate  1 , a first chip  12 , a spacer  13 , a second chip  14 , a plurality of first wires  15 , a plurality of second wires  16  and a molding material  17 . 
     The substrate  11  has an upper surface  111  and a lower surface  112 . The first chip  12  has an upper surface  121  and a lower surface  122 . The lower surface  122  of the first chip  12  is attached to the upper surface  111  of the substrate  11  by a first adhesive  181 . The spacer  13  is attached to the upper surface  121  of the first chip  12  by a second adhesive  182 . The second chip  14  has an upper surface  141  and a lower surface  142 . The lower surface  142  of the second chip  14  is attached to the spacer  13  by a third adhesive  183 . The first wires  15  are electrically connected to the upper surface  121  of the first chip  12  and the upper surface  111  of the substrate  11 . The second wires  16  are electrically connected to the upper surface  141  of the second chip  14  and the upper surface  111  of the substrate  11 . The molding material  17  is used to cover the upper surface  111  of the substrate  11 , the first chip  12 , the spacer  13 , the second chip  14 , the first wires  15  and the second wires  16 . 
     In the conventional stacked semiconductor package  1 , in order to avoid the second chip  14  damaging the first wires  15  due to its weight, a thicker spacer  13  is set up to support the second chip  14  to increase the distance between the first chip  12  and the second chip  14 . However, it not only increases the total height of the semiconductor package  1 , but also the alignment of the spacer  13  is difficult during the process and therefore the misalignment easily damages the first wires  15 . 
     Therefore, a novel and inventive stacked semiconductor package must be provided to solve the problem. 
     SUMMARY OF THE INVENTION 
     The main purpose of the present invention provides a stacked semiconductor package having a flexible circuit board therein. The stacked semiconductor package includes a substrate and a chip assembly. The chip assembly includes at least a first chip, a second chip and a flexible circuit board. The second chip is disposed above the first chip and is connected to the first chip through the flexible circuit board and the chip assembly is electrically connected to the substrate. By doing so, the conventional spacer may be omitted, so that the total height of the semiconductor package can be effectively reduced and the process can be simplified to reduce the cost. 
     These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a cross-sectional view of a conventional stacked semiconductor package. 
         FIG. 2  illustrates a cross-sectional view of a first embodiment of the stacked semiconductor package having flexible circuit board therein of the present invention. 
         FIG. 3  illustrates a cross-sectional view of a second embodiment of the stacked semiconductor package having flexible circuit board therein of the present invention. 
         FIG. 4  illustrates a cross-sectional view of a third embodiment of the stacked semiconductor package having flexible circuit board therein of the present invention. 
         FIG. 5  illustrates a cross-sectional view of a fourth embodiment of the stacked semiconductor package having flexible circuit board therein of the present invention. 
         FIG. 6  illustrates a cross-sectional view of a fifth embodiment of the stacked semiconductor package having flexible circuit board therein of the present invention. 
         FIG. 7  illustrates a cross-sectional view of a sixth embodiment of the stacked semiconductor package having flexible circuit board therein of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     Please refer to  FIG. 2 , illustrating a cross-sectional view of a first embodiment of the stacked semiconductor package having flexible circuit board therein of the present invention. The stacked semiconductor package  2  of the embodiment includes a substrate  21  and a chip assembly  22 . The substrate  21  has an upper surface  211  and a lower surface  212 . The chip assembly  22  includes a first chip  221 , a second chip  222  and a flexible circuit board  223 . The first chip  221  has an upper surface  2211  and a lower surface  2212 . The second chip  222  has an upper surface  2221  and a lower surface  2222 . The second chip  222  is disposed above the first chip  221  and is electrically connected to the first chip  221  through the flexible circuit board  223 . The flexible circuit board  223  has a plurality of parallel wires, whose ends may be connected to the corresponding solder pads on the chips. 
     In this embodiment, the flexible circuit board  223  connects the upper surface  2221  of the second chip  222  and the lower surface  2212  of the first chip  221 , and the lower surface  2212  of the first chip  221  is attached to the upper surface  211  of the substrate  21  by way of flip-chip, so that the chip assembly  22  may be electrically connected to the substrate  21 . In addition, if necessary, a molding material (not shown) may be added to cover the chip assembly  22  and the upper surface  211  of the substrate  21 . 
     In this embodiment, the conventional spacer may be omitted so that the total height of the semiconductor package can be effectively reduced and the process can be simplified to reduce the cost. 
     Please refer to  FIG. 3 , illustrating a cross-sectional view of a second embodiment of the stacked semiconductor package having flexible circuit board therein of the present invention. The stacked semiconductor package  3  of the embodiment includes a substrate  31  and a chip assembly  32 . The substrate  31  has an upper surface  311  and a lower surface  312 . The chip assembly  32  includes a first chip  321 , a second chip  322  and a flexible circuit board  323 . The first chip  321  has an upper surface  3211  and a lower surface  3212 . The second chip  322  has an upper surface  3221  and a lower surface  3222 . The second chip  322  is disposed above the first chip  321  and is electrically connected to the first chip  321  through the flexible circuit board  323 . The flexible circuit board  323  has a plurality of parallel wires, whose ends may be connected to the corresponding solder pads on the chips. 
     In this embodiment, the flexible circuit board  323  connects the upper surface  3221  of the second chip  322  and the lower surface  3212  of the first chip  321 , and the stacked semiconductor package  3  further includes a spacer  33 , a plurality of wires  34  and a molding material  35 . The spacer  33  is disposed between the lower surface  3212  of the first chip  321  and the upper surface  311  of the substrate  311 . The wires  34  electrically connect the upper surface  3221  of the second chip  322  and the upper surface  311  of the substrate  31 , so that the chip assembly  32  may be electrically connected to the substrate  31 . The molding material  35  covers the chip assembly  32 , the spacer  33 , the wires  34  and the upper surface  311  of the substrate  31 . To facilitate the flow of the molding material  35 , the flexible circuit board  323  has a plurality of holes (not shown). It is understandable that these holes are parallel with the wires on the flexible circuit board  323 . 
     In this embodiment, the thickness of the spacer  33  may be thinner than the conventional spacer so that the total height of the semiconductor package  3  can be effectively reduced. 
     Please refer to  FIG. 4 , illustrating a cross-sectional view of a third embodiment of the stacked semiconductor package having flexible circuit board therein of the present invention. The stacked semiconductor package  4  of the embodiment includes a substrate  41  and a chip assembly  42 . The substrate  41  has an upper surface  411  and a lower surface  412 . The chip assembly  42  includes a first chip  421 , a second chip  422  and a flexible circuit board  423 . The first chip  421  has an upper surface  4211  and a lower surface  4212 . The second chip  422  has an upper surface  4221  and a lower surface  4222 . The second chip  422  is disposed above the first chip  421  and is electrically connected to the first chip  421  through the flexible circuit board  423 . The flexible circuit board  423  has a plurality of parallel wires, whose ends may be connected to the corresponding solder pads on the chips. 
     In this embodiment, the flexible circuit board  423  connects the upper surface  4221  of the second chip  422  and the lower surface  4212  of the first chip  421 , and the flexible circuit board  423  further includes a branch circuit board  4231  for connecting to the upper surface  411  of the substrate  41  so that the chip assembly  42  is electrically connected to the substrate  41 . The stacked semiconductor package  4  further includes a spacer  43 , which is disposed between the lower surface  4212  of the first chip  421  and the upper surface  411  of the substrate  41 . 
     Please refer to  FIG. 5 , illustrating a cross-sectional view of a fourth embodiment of the stacked semiconductor package having flexible circuit board therein of the present invention. The stacked semiconductor package  5  of the present invention resembles the stacked semiconductor package  2  ( FIG. 2 ) of the first embodiment and similar parts share similar numbers. The difference between the stacked semiconductor package  5  and the stacked semiconductor package  2  resides in the connection of the flexible circuit board  223 . In the stacked semiconductor package  5  of the embodiment, the flexible circuit board  223  connects the upper surface  2221  of the second chip  222  and the upper surface  2211  of the first chip  221 . 
     Please refer to  FIG. 6 , illustrating a cross-sectional view of a fifth embodiment of the stacked semiconductor package structure having flexible circuit board therein of the present invention. The stacked semiconductor package  6  of the present invention resembles the stacked semiconductor package  3  ( FIG. 3 ) of the second embodiment and similar parts share similar numbers. The difference between the stacked semiconductor package  6  and the stacked semiconductor package  3  of the second embodiment resides in the connection of the flexible circuit board  323 . In the stacked semiconductor package  6  of the embodiment, the flexible circuit board  323  connects the upper surface  3221  of the second chip  322  and the upper surface  3211  of the first chip  321 . 
     Please refer to  FIG. 7 , illustrating a cross-sectional view of a sixth embodiment of the stacked semiconductor package structure having flexible circuit board therein of the present invention. The stacked semiconductor package  7  of the present invention resembles the stacked semiconductor package  4  ( FIG. 4 ) of the third embodiment and similar parts share similar numbers. The difference between the stacked semiconductor package  7  and the stacked semiconductor package  4  of the third embodiment resides in the connection of the flexible circuit board  423 . In the stacked semiconductor package  7  of the embodiment, the flexible circuit board  423  connects the upper surface  4221  of the second chip  422  and the upper surface  4211  of the first chip  421 . 
     Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.