Patent Publication Number: US-2006016973-A1

Title: Multi-chip image sensor package module

Description:
FIELD OF THE INVENTION  
      The present invention relates to an image sensor package module, and more particularly to a multi-chip image sensor package module for accommodating an image sensor chip at low cost.  
     BACKGROUND OF THE INVENTION  
      Conventionally, an image sensor chip is integrated in a package module with other IC chips such as digital signal processor, IC, for electrical integrity. However, the dimension and thickness of the package module will increase. As disclosed in U.S. Pat. No. 6,686,588, a conventional image sensor package module includes an image sensor chip and electronic components connected to a substrate. The image sensor chip is attached to the upper surface of the substrate by adhesive. A sidewall with locking features is mounted on the upper surface to form a chip cavity for accommodating the image sensor chip and to assemble with a lens housing. The electronic components and solder balls are disposed on the lower surface of the substrate to form a package module. The package module is thicker and has a higher packaging cost.  
     SUMMARY OF THE INVENTION  
      A main purpose of the present invention is to provide a multi-chip image sensor package module comprising a substrate having an opening, an IC chip, an image sensor chip and a glass cover/lens. The IC chip including bumps is flip-chip mounted on the lower surface of the substrate. A chip cavity consists of the IC chip, the bumps and the opening of the substrate. The image sensor chip is disposed between the substrate and the IC chip so that the sensing region of the image sensor chip is aligned with the glass cover/lens via the opening. The package thickness of the multi-chip image sensor package module and the assemble cost can be reduced.  
      According to the present invention, a multi-chip image sensor package module comprises a substrate having an opening, an IC chip, an image sensor chip and a glass cover/lens. The opening is formed through the upper and lower surfaces of the substrate. The IC chip has a mounting surface and includes a plurality of bumps on the mounting surface. The IC chip is mounted on the lower surface of the substrate via the bumps. The bumps is formed at the peripheral region of the mounting surface without blocking the central region of the mounting surface, so that a chip cavity consists of the central region of the IC chip, the bumps and the opening of the substrate. The image sensor chip has an active surface and a backside surface. The active surface includes a sensing region smaller than the opening of the substrate. Moreover, the image sensor chip is disposed between the substrate and the IC chip inside the chip cavity in a manner that the sensing region is aligned with the glass cover/lens through the opening. Preferably, the central region of the mounting surface of the IC chip is no any bumps formed and is larger than the backside surface of the image sensor chip. The backside surface of the image sensor chip can be closer to the central region of the IC chip by chip-to-chip attachment on the central region or flip-chip mounting on the substrate. The glass cover/lens is disposed above the upper surface of the substrate to assemble a thin module. 
    
    
     DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is the cross-sectional view of the multi-chip image sensor package module according to the first embodiment of the present invention.  
       FIG. 2  is the cross-sectional view of the multi-chip image sensor package module according to the second embodiment of the present invention.  
       FIG. 3  is the cross-sectional view of the multi-chip image sensor package module according to the third embodiment of the present invention. 
    
    
     DETAIL DESCRIPTION OF THE INVENTION  
      Please refer to the drawings attached, the present invention will be described by means of embodiments below.  
      According to the first embodiment of the present invention, a multi-chip image sensor package module  100  is illuminated as shown in  FIG. 1 , which mainly includes a substrate  110 , an IC chip  120  and an image sensor chip  130  and a lens  142 . The substrate  110  may have a multi-layer circuits structure, such as a multi-layer co-fired ceramic, a MLCC, a printed circuited board (PCB), or a leadframe-based circuit board, for electrical connection of the IC chip  120  and the image sensor chip  130 . The substrate  110  has an upper surface  111 , a lower surface  112 , and an opening  113  through the upper surface  111  and the lower surface  112 .  
      According to the present embodiment, the IC chip  120  may be a flip chip or a chip scale package (CSP). The IC chip  120  has a mounting surface  121  and includes a plurality of bumps  122  formed on the mounting surface  121  of the IC chip  120 . In this embodiment, the IC chip  120  is a DSP (Digital Signal Processor). The IC chip  120  is flip-chip mounted on the lower surface  112  of the substrate  110  via the bumps  122 . The mounting surface  121  includes a central region  123  corresponding the backside surface  132  of the image sensor chip  130  and a peripheral region  124  around the central region  123 . Bumps  122  are formed at the peripheral region  124  of the mounting surface  121  without blocking the central region  123 . Therefore a chip cavity is formed which consists of the central region  123  of the IC chip  120 , the bumps  122  and the opening  113  of the substrate  110 . The image sensor chip  130  is disposed between the IC chip  120  and the substrate  110  inside the chip cavity, and can be even closer to the central region  123  of the IC chip  120 . Furthermore, the dimension of the IC chip  120  should be larger than the image sensor chip  130 .  
      The image sensor chip  130  has an active surface  131  and a backside surface  132 . The active surface  131  includes a sensing region  133  for sensing images. The sensing region  133  is smaller than the opening  113  of the substrate  110 . According to the embodiment, the opening  113  of the substrate  110  is smaller than the active surface  131  of the image sensor chip  130 . The image sensor chip  130  is electrically connected to the substrate  110  by flip-chip mounting. The image sensor chip  130  includes a plurality of flip-chip bumps  134  to mount on the lower surface  112  of the substrate  110 , wherein the sensing region  133  is aligned with the opening  113  of the substrate  110 . Moreover, the area of the central region  123  of the IC chip  120  is almost equal to the area of the backside surface  132  of the image sensor chip  130 . The bumps  122  connecting the lower surface  112  of the substrate  110  have a height larger than the thickness of the image sensor chip  130 , so that the image sensor chip  130  can be disposed between the IC chip  120  and the substrate  110 , and the active surface  131  and the backside surface  132  of the image sensor chip  130  are formed between the mounting surface  121  of the IC chip  120  the lower surface  112  of the substrate  110 . The thickness of the multi-chip image sensor package module  100  can be reduced.  
      According to this embodiment, a lens module  140  is mounted on the upper surface  111  of the substrate  110 . The lens module  140  includes a lens housing  141  to connect the lens  142 . The lens housing  141  is airtightly connected to the substrate  110 . Moreover, the lens  142  is aligned with the sensing region  133  of the image sensor chip  130  through the opening  113 . Furthermore, a glass cover  143  is disposed above the upper surface  111  of the substrate  110  and is also aligned with the sensing region  133  of the image sensor chip  130  through the opening  113 . According to this embodiment, the glass cover  143  is an IR-cut filter and is supported by the lens housing  141 . Preferably, at least one passive component  150  is connected to the upper surface  111  or the lower surface  112 . Moreover, an outer electrical connector  160 , such as a flexible connector, can be connected to the lower surface  112  of the substrate  110  for outer connection.  
      In the multi-chip image sensor package module  100  mentioned above, the image sensor chip  130  is located between the substrate  110  and the IC chip  120  inside a composite chip cavity to achieve a thin module. Preferably, the package module  100  includes a filling material  170 , such as a non-flow underfilling material, a non-conductive paste (NCP), or an anisotropic conductive paste (ACP). The filling material  170  is formed between the mounting surface  121  of the IC chip  120  and the lower surface  112  of the substrate  110  without contaminating the sensing region  133  of the image sensor chip  130  to encapsulate the bumps  122  and seal the image sensor chip  130 . Therefore, the image sensor chip  130  is surrounded by an airtight space formed by the IC chip  120 , the filling material  170 , the opening  113  of the substrate  110  and the lens module  140  so that a thinner package module with lower package cost and excellent yield can be achieved.  
      According to the second embodiment of the present invention, as shown in  FIG. 2 . A multi-chip image sensor package module  200  mainly includes a substrate  210  having a opening  213 , an IC chip  220 , an image sensor chip  230  and a glass cover  241 . The opening  213  passes through the upper surface  211  and the lower surface  212  of the substrate  210 , and is larger than the image sensor chip  230  in size. A mounting base  242  connecting the glass cover  241  is mounted on the upper surface  211 . The substrate  210  has a protruding layer  214  which is formed on periphery of the lower surface  212  for accommodating the IC chip  220 . Moreover, the opening  213  of the substrate  210  has a stepping portion  215  toward the lower surface  212 . The image sensor chip  230  is flip-chip mounted on the stepping portion  215  via a plurality of flip-chip bumps  234 . The IC chip  220  is also mounted on the lower surface  212  inside the protruding layer  214 . The IC chip  220  has a mounting surface  221  which includes a central region  223  and a peripheral region  224 . A plurality of bumps  222  are formed at the peripheral region  224  of the mounting surface  221  without blocking the central region  223 . The bumps  222  are connected on the lower surface  212  of the substrate  210 . A chip cavity consists of the central region  223  of the IC chip  220 , the bumps  222  and the opening  213  of the substrate  210  for accommodating the image sensor chip  230 . The image sensor chip  230  has an active surface  231  and a backside surface  232 . The active surface  231  includes a sensing region  233  smaller than the opening  213  of the substrate  210 . The image sensor chip  230  includes a plurality of bumps  234 , so that the image sensor chip  230  can be flip-chip mounted on the stepping portion  215  of the substrate  210 . The image sensor chip  230  is disposed between the IC chip  220  and the substrate  210  in a manner that the sensing region  233  is aligned with the glass cover  241  through the opening  213  of the substrate  210 . Moreover, the active surface  231  of the image sensor chip  230  is formed in the opening  213  between the upper surface  211  and the lower surface  212  of the substrate  210 . Preferably, a plurality of passive components  250  are connected to the upper surface  211  and the lower surface  212  of the substrate  210 . An outer electrical connector  260  is connected to the protruding portion  214  of the substrate  210  for outer electrical connection of the multi-chip image sensor package module  200 . Therefore, the thickness of the multi-chip image sensor package module  200  can be thinner with lower assemble cost.  
      According to the third embodiment of the present invention, as shown in  FIG. 3 . A multi-chip image sensor package  300  mainly includes a substrate  310  having an opening  313 , an IC chip  320 , and an image sensor chip  330 . The opening  313  of the substrate  310  passes through the upper surface  311  and the lower surface  312 . The opening  313  is smaller than the sensing region  333  of the image sensor chip  330 . In this embodiment, the opening  313  is larger than the active surface  331  of the image sensor chip  330 . A lens module  340  having a lens  341  can be mounted on the upper surface  331  of the substrate  310 . Preferably, the substrate  310  comprises a protruding layer  314  which is formed on the lower surface  312  for accommodating the IC chip  320 . The IC chip  320  has a mounting surface  321  which includes a central region  323 . A plurality of bumps  322  are formed at the peripheral region  324  of the mounting surface  321  without blocking the central region  323 . The bumps  322  connect the lower surface  312  of the substrate  310 . The image sensor chip  330  has an active surface  331  and a backside surface  332 . The active surface  331  includes a sensing region  333  smaller than the opening  313 . The backside surface  332  of the image sensor chip  330  can be attached to the central region  323  of the IC chip  320  by adhesive, the image sensor chip  330  is disposed between the substrate  310  and the IC chip  320  in a manner that the sensing region  333  is aligned with the lens  341  through the opening  313 . The image sensor chip  330  is electrically connected to the substrate  310  via a plurality of bonding wires  334  so that the image sensor chip  330  can be stacked on the IC chip  320 . The active surface  331  of the image sensor chip  330  is formed in the opening  313  between the upper surface  311  and the lower surface  312  of the substrate  310 . Therefore, the thickness of the multi-chip image sensor package module  300  can be thinner with lower assemble cost.  
      The above description of embodiments of this invention is intended to be illustrative and not limiting. Other embodiments of this invention will be obvious to those skilled in the art in view of the above disclosure.