Abstract:
A heat-dissipating interposer includes an insulating base, a plurality of conductive pillars and a thermal conducting frame. The insulating base includes a first surface and an opposite second surface. The conductive pillars are arranged on the insulating base. The conductive pillars protrude from the second surface. The height of the conductive pillars relative to the second surface is greater than the thickness of the insulating base. The thermal conducting frame is placed on the second surface and receives a heat-generating component. The interposer can be used in a package on package structure.

Description:
BACKGROUND 
     1. Technical Field 
     The present disclosure relates to packaging structures for semiconductor devices, particularly to an interposer and a package on package (POP) structure including the interposer. 
     2. Description of Related Art 
     In order for a POP structure to attain a high density integrated layout and a small area installation, two electric elements are electrically connected by a plurality of solder balls. The diameter of the solder ball may be in the range from 200 um to 300 um which is quite large. It is difficult to reduce the volume of the POP structure due to the large diameters of the solder ball and the large size of contact pad corresponding to the solder ball. The structural strength and integrity of the connection between the solder ball and the contact pad is not optimal due to the large diameter of the solder ball. So, the reliability of POP structure is not good. In addition, the bottom one of the two electric elements is usually provided between two circuit boards. Heat created by the bottom electric elements is hard to dissipate due to undesirable insulation given by the two circuit boards. 
     What is needed, therefore, is a POP structure that can overcome the described limitations. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present embodiments can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a schematic, cross-sectional view of an interposer according to a first embodiment. 
         FIG. 2  is a bottom view of the interposer of  FIG. 1 . 
         FIG. 3  is a schematic, cross-sectional view of an interposer according to a second embodiment. 
         FIG. 4  is a schematic, cross-sectional view of an interposer according to a third embodiment. 
         FIGS. 5-7  are schematic, cross-sectional views of a POP structure. 
     
    
    
     DETAILED DESCRIPTION 
     An interposer and a POP structure will be described with reference to the drawings. 
       FIGS. 1-2  show an interposer  100  according to a first embodiment. The interposer  100  includes an insulating base  110 , a plurality of electric conductive pillars  120 , and a thermal conductive frame  130 . 
     The insulating base  110  includes a first surface  111  and a second surface  112  opposite to the first surface  111 . A plurality of through holes  113  is defined in the insulating base  110 . The through holes  113  are separated from each other. A groove  114  is defined in the first surface  112  to the inside of the insulating base  110 . 
     The electric conductive pillars  120  are aligned with and arranged in the through holes  113 . An electric conductive pillar  120  includes a first end face  121  and a second end face  122  opposite to the first end face  121 . A height of each electric conductive pillar  120  is greater than the thickness of the insulating base  110  in this embodiment. The first end face  121  and the first surface  111  are coplanar. The second end face  122  protrudes from the second surface  112 . The height of the electric conductive pillar  120  relative to the second surface  112  is greater than the thickness of the insulating base  110 . Extension direction of the electric conductive pillar  120  is perpendicular to the second surface  112 . 
     A portion of the thermal conductive frame  130  is received in the insulating base  110 . The thermal conductive frame  130  includes a top plate  131  and a plurality of thermal conductive pillars  132  perpendicularly interconnected with the top plate  131 . The top plate  131  is received in the groove  114 . The thermal conductive pillars  132  perpendicularly extend from the border of the top plate  131 . There is no thermal conductive pillar  132  formed on the middle area of the top plate  131 . Extension direction of the thermal conductive pillar  132  is equal to that of the electric conductive pillar  120 . The material of the thermal conductive frame  130  is thermally conductive metal such as copper, aluminum, or silver. In one embodiment, the material of the thermal conductive frame  130  is copper, is the same as that of the electric conductive pillar  120 . In one embodiment, the height of the electric conductive pillar  120  relative to the insulating base  110  is equal to that of the thermal conductive pillar  132  relative to the insulating base  110 . 
     The interposer  100  also includes a plurality of first contact pads  150 . The first contact pads  150  are formed on the first surface  111 . The first contact pads  150  are aligned with the electric conductive pillars  120 . The first contact pad  150  is electrically connected with the first end face  121  of an electric conductive pillar  120 . 
     In an alternative embodiment, a solder mask layer  101  is formed on the first surface  111 . A plurality of openings  1011  are defined in the solder mask layer  101 . The first contact pads  150  are exposed through the openings  1011 . 
       FIG. 3  shows an interposer  200  according to a second embodiment. The structure of the interposer  200  is similar to that of the interposer  100  of the first embodiment. The interposer  200  includes an insulating base  210 , a plurality of electric conductive pillars  220 , a thermal conductive connector  240 , a plurality of conductive vias  250 , and a thermal conductive frame  230 . 
     The insulating base  210  includes a first surface  211  and a second surface  212  opposite to the first surface  211 . A plurality of through holes  213  is defined in the insulating base  210 . The diameter of the through hole  213  gradually reduces from the first surface  211  to the second surface  212 . 
     The electric conductive pillars  220  are aligned with the conductive vias  250 . Extension direction of the electric conductive pillars  220  is perpendicular to the second surface  212 . A height of each electric conductive pillar  220  is greater than the thickness of the insulating base  210 . 
     The thermal conductive frame  230  is formed on the second surface  212 . The thermal conductive frame  230  includes a top plate  231  and a plurality of thermal conductive pillars  232 . The top plate  231  includes a top surface  2311  facing away from the thermal conductive pillars  232 . The top surface  2311  is in contact with the second surface  212 . The top surface  2311  and the second surface  212  are coplanar. The thermal conductive pillars  232  perpendicularly extend from the border of the top plate  231 . There is no thermal conductive pillar  232  formed on the middle area of the top plate  131 . The material of the thermal conductive frame  230  is thermally conductive metal such as copper, aluminum, or silver. In one embodiment, the material of the thermal conductive frame  230  is copper and is same as that of the electric conductive pillar  220 . 
     The thermal conductive connector  240  is also formed on the second surface  212 . The thermal conductive connector  240  interconnects between the thermal conductive frame  230  and an electric conductive pillar  220 . 
     The interposer  200  also includes a plurality of first contact pads  260 . The first contact pad  260  is defined on the first surface  211 . Each of the first contact pads  260  is electrically connected with a conductive via  250 . In one embodiment, the first contact pad  260  and the conductive via  250  corresponding to the first contact pad  260  are integrated. 
       FIG. 4  shows an interposer  300  according to a third embodiment. The structure of the interposer  300  is similar to that of the interposer  100  of the first embodiment. The interposer  300  includes an insulating base  310 , a plurality of electric conductive pillars  320 , and a thermal conductive frame  330 . 
     The insulating base  310  includes a first surface  311  and a second surface  312  opposite to the first surface  311 . A plurality of through holes  313  is defined in the insulating base  310 . The through holes  313  are separated from each other. A receiving hole  314  is defined in the second surface  311  through to the first surface  312 . The receiving hole  314  is surrounded by the through holes  313 . 
     The electric conductive pillars  320  are aligned with and received in the through holes  313 . The electric conductive pillar  320  includes a first end face  321  and a second end face  322  opposite to the first end face  321 . The height of each electric conductive pillar  320  is greater than the thickness of the insulating base  310  in this embodiment. The first end face  321  and the first surface  311  are coplanar. The second end face  322  protrudes from the second surface  312 . A height of the electric conductive pillar  320  relative to the second surface  312  is greater than the thickness of the insulating base  310 . 
     The thermal conductive frame  330  is partially received in the receiving hole  314 . The thermal conductive frame  330  includes a top plate  331  and a plurality of thermal conductive pillars  332  perpendicularly interconnected with the top plate  331 . The top plate  331  includes a top surface  3311  facing away from the thermal conductive pillars  332 . The top surface  3311  and the first surface  311  are coplanar. The thermal conductive pillars  332  perpendicularly extend from the border of the top plate  331 . Extension direction of the thermal conductive pillar  332  is equal to that of the electric conductive pillar  320 . The material of the thermal conductive frame  330  is thermally conductive metal such as copper, aluminum, or silver. In one embodiment, the material of the thermal conductive frame  330  is copper, the same as that of the electric conductive pillar  320 . 
     The interposer  300  also includes a plurality of first contact pads  350 . The first contact pad  350  is defined on the first surface  311 . Each of the first contact pads  350  is aligned with and electrically connected with an electric conductive pillar  320 . 
     In an alternative embodiment, a solder mask layer is formed on the first surface of the second or the third embodiment. A plurality of openings is defined in the solder mask layer. The first contact pads are exposed through the corresponding openings. 
     The interposer can also includes a thermal conductive connector of the first or the third embodiment. The thermal conductive frame and some of the electric conductive pillars are interconnected through the thermal conductive connectors. 
       FIG. 5  shows a POP structure  10  according to a fourth embodiment. The POP structure  10  includes a first package substrate  20 , a first chip  30 , a second package substrate  40 , a second chip  50 , a first solder  60 , a second solder  70 , and an interposer of the first embodiment, the second embodiment, or the third embodiment. In this embodiment, an interposer  100  is provided according to the first embodiment. 
     The first package substrate  20  includes a first base layer  21 , a first circuit layer  22 , a second circuit layer  23 , a first solder mask layer  24 , a second solder mask layer  25 , and a plurality of solder balls  26 . The first circuit layer  22  and the second circuit layer  23  are formed on the opposite surface of the first base layer  21 . The first solder mask layer  24  is formed on the surface of the first circuit layer  22 . The second solder mask layer  25  is formed on the surface of the second circuit layer  23 . 
     The first base layer  21  is a multilayer substrate. The first base layer  21  includes a plurality of resin layers alternating with a plurality of circuit layers. The first base layer  21  includes a third surface  2110  and a fourth surface  2120  opposite to the third surface  2110 . The first circuit layer  22  is formed on the third surface  2110 . The second circuit  23  is formed on the fourth surface  2120 . In one embodiment, the first circuit layer  22 , the second circuit layer  23 , and the other circuit layer of the first base layer  21  are electrically connected through a plurality of conductive vias. 
     Portions of the first circuit layer  22  are exposed through the first solder mask layer  24 . The exposed portions of the first circuit layer  22  are defined to be a plurality of third contact pads  2210  and a plurality of fourth contact pads  2220 . The third contact pads  2210  are arranged in an array. The third contact pads  2210  are surrounded by the fourth contact pads  2220 . 
     Portions of the second circuit layer  23  are exposed through the second solder mask layer  25 . The exposed portions of the second circuit layer  23  are defined to be a plurality of fifth contact pads  2310 . The fifth contact pads  2310  are arranged in an array. The third contact pads  2210 , the fourth contact pads  2220  and the fifth contact pads  2310  are electrically connected through circuit layers and conductive holes. 
     Each of the solder balls  26  is aligned with and is attached on a fifth contact pad  2310 . 
     The first chip  30  is packed on the first solder mask layer  24  side of the first package substrate  20  by a flip-chip technology. The first chip  30  is adhered on the first solder mask layer  24  by a first packaging adhesive  32 . The first packaging adhesive  32  is made of high heat dissipation material such as thermally conductive adhesive. The first chip  30  includes a plurality of contact pads aligned with the third contact pads  2210 . The contact pads of the first chip  30  and the corresponding third contact pads  2210  are electrically interconnected by conductive holes  31 . The first chip  30  is received in the thermal conductive frame  130 . The first chip  30  and the top plate  131  are interconnected through a heat dissipation bonding sheet  33  for quickly dissipating to the top plate  131  heat created by the first chip  30 . 
     The electric conductive pillars  120  are aligned with and electrically connected with the fourth contact pads  2220  through the first solder  60 . 
     The second package substrate  40  includes two conductive layers. The second package substrate  40  is formed on the interposer  100  and opposite to the first package substrate  20 . The second package substrate  40  includes a second base layer  42 , a third circuit layer  43 , a fourth circuit layer  44 , a third solder mask layer  45 , and a fourth solder mask layer  46 . The third circuit layer  43  and the fourth circuit layer  44  are formed on the opposite surface of the second base layer  42 . The third solder mask layer  45  is formed on the surface of the third circuit layer  43 . The fourth solder mask layer  46  is formed on the surface of the fourth circuit layer  44 . 
     The second base layer  42  includes a fifth surface  421  and a sixth surface  422  opposite to the fifth surface  421 . The third circuit layer  43  is formed on the fifth surface  421 . The fourth circuit  44  is formed on the sixth surface  422 . The third circuit layer  43  and the fourth circuit layer  44  are electrically connected through a plurality of conductive vias  47 . The second base layer  42  is an insulating material or an inner circuit board including circuit layers and insulating layers. 
     Portions of the third circuit layer  43  are exposed through the third solder mask layer  45 . The exposed portions of the third circuit layer  43  are defined to be a plurality of sixth contact pads  431 . A chip fixing area is defined on the third solder mask layer  45 . The chip fixing area is surrounded by the sixth contact pads  431 . 
     Portions of the fourth circuit layer  44  are exposed through the fourth solder mask layer  46 . The exposed portions of the fourth circuit layer  44  are defined to be a plurality of seventh contact pads  441 . The seventh contact pads  441  are aligned with the first contact pads  150 . The seventh contact pad  441  and the first contact pad  150  are electrically connected through the second solder  70 . The sixth contact pads  431  and the seventh contact pads  441  are electrically connected through the third circuit layer  43 , the fourth circuit layer  44 , and the conductive vias  47 . 
     The second chip  50  is attached on the third solder mask layer  45 . In one embodiment, the second chip  50  is a wire bonding chip. The second chip  50  is electrically interconnected with the sixth contact pads  431 . In detail, the second chip  50  includes a plurality of soldering contacts and a plurality of soldering wires  501  extended from the soldering contacts. The soldering wires  501  are aligned with and electrically connected with the sixth contact pads  431 . The second chip  50  and the third circuit layer  43  are electrically connected through the soldering wires  501 . 
     In one embodiment, the second chip  50  is adhered on the chip fixing area of the third solder mask layer  45  through a adhesive layer. The soldering wires  501  are soldered with the sixth contact pads  431 . The material of the soldering wires  501  is gold. The soldering wires  501 , the second chip  50 , the third solder mask layer  45  and the sixth contact pads  431  are all covered by a second packaging adhesive  502 . The second packaging adhesive  502  is black gum or other packaging adhesive. 
     The interposer  100  and the second package substrate  40  are also covered by the second packaging adhesive  502  if the cross-section area of the first package substrate  20  is greater than that of the interposer  100  and the second package substrate  40 . The interposer  100  and the second package substrate  40  are also covered by the second packaging adhesive  502  in this embodiment. 
     In this embodiment, the first chip  30  is received in the thermal conductive frame  130 , thus heat created by the first chip  30  can be dissipated to the thermal conductive frame  130  and out of the POP structure  10 . Therefore, the disclosed POP structure  10  provides better heat dissipation. 
       FIG. 6  shows a POP structure including an interposer of the second embodiment. The seventh contact pads  441  are electrically connected with the correspondingacco conductive vias or the first contact pads  250  through the second solder  70 . The thermal conductive connector  240  is interconnected between the thermal conductive frame  230  and an electric conductive pillar  220 . Therefore, the heat created by the first chip can be dissipated to the electric conductive pillar  220 , and thence to the first package substrate  20  and the second package substrate  40  through the thermal conductive frame  230 . Thus, the disclosed POP structure  10  provides improved heat dissipation. 
       FIG. 7  shows a POP structure including an interposer according to the third embodiment. The top surface  3311  of the top plate  331  and the first surface  311  are coplanar. Therefore, the overall thickness of the POP structure is decreased. 
     While certain embodiments have been described and exemplified above, various other embodiments will be apparent to those skilled in the art from the foregoing disclosure. The present disclosure is not to be limited to the particular embodiments described and exemplified but is capable of considerable variation and modification without departure from the scope of the appended claims.