Patent Publication Number: US-2004056971-A1

Title: Thin type camera module

Description:
FIELD OF THE INVENTION  
       [0001] The present invention is relating to a camera module, particularly to a thin type camera module comprises an image-sensing semiconductor assembly manufactured by Chip-On-Film technology.  
       BACKGROUND OF THE INVENTION  
       [0002] Application fields of a camera module are wide, such as digital camera, video telephone, video conference system. Normally the camera module includes a package having an image sensing chip (such as CMOS) inside an optical device for capturing image information. The camera module is converting the image information to the digital signal and transporting to a circuit board for identifying or storing the image information.  
       [0003] A conventional CCD image sensing module was disclosed in R.O.C. Taiwan Patent No. 492593 entitled “CCD and CMOS image capturing module”. The CCD and CMOS image capturing module comprises a image sensing device which is electrically connecting to a circuit board. A lens holder is mounted on the circuit board and seals the image sensing device. Because that the circuit board forms a module circuit which is for connecting to the image sensing device, the process flow of the CCD and CMOS image capturing module is that firstly connecting the image sensing device to the circuit board, then fixing the lens holder and the circuit board. The CCD and CMOS image capturing module would cause the lens holder and the image sensing device misalignment, and capturing angle of the image sensing device is easy to deviate. Another improved structure of the CCD and CMOS image capturing module which is similar to the foregoing CCD and CMOS image capturing module are brought from the known patent. But the lens holder is connecting onto mold body of the image sensing device (CMOS or CCD). Besides, the lens holder is attached and sealed the top edge of the mold body of the image sensing device. However, the lens holder is connecting on the image sensing device, the image sensing device has to sustain the weight of the whole lens holder. The stability between the image sensing device and circuit board would be poor.  
       [0004] Another conventional electric camera lens module was disclosed in R.O.C Taiwan. Patent No. 372079 entitled “electric camera lens module”. The electric camera lens module comprises a lens holder and a photosensitive module, wherein a plane of the lens holder disposes a hollow pillar which is set an adjustable cone, another plane of the lens holder disposes a trough which is linking the hollow pillar. The photosensitive module is installed in the trough, which comprises a filter, a hard substrate with pins and a photosensitive chip, wherein the substrate has a through hole at corresponding the hollow pillar for setting the filter. The photosensitive chip has a photosensitive surface corresponding to the through hole and the pillar, and has a plurality of contact ends contacted with pins of the substrate through the signal circuit of the substrate. When the pins electrically contact with an exterior electronic device, the electric camera lens module will start to capture image. Because of the photosensitive module is assembled by the filter, the hard substrate and the photosensitive chip, wherein the photosensitive chip is disposed at the bottom of the substrate in bare-chip configuration, so that protection of the photosensitive chip is poor. The whole thickness of the electric camera lens module is thicker, because the thickness of the photosensitive module has to consider the thickness of the filter, the hard substrate and the photosensitive chip, and the length of the pins of the hard substrate.  
       SUMMARY  
       [0005] The primary object of the present invention is to provide a thin type camera module comprises an image-sensing semiconductor assembly which is manufacture by a chip-on-film (COF) packaging method, so the thin type camera module is thinner. Besides, a fixing board forms a recession for holding an image sensing chip in order to achieve more thinner thin type camera module.  
       [0006] The second object of the present invention is to provide a thin type camera module comprises an image-sensing semiconductor assembly which is manufacture by a COF packaging method. An image sensing chip is flip-chip mounted on a COF wiring film, so the reliability is better. And the COF wiring film is suited for continue mass production the image-sensing semiconductor assembly to reduce the thin type camera module running cost.  
       [0007] The third object of the present invention is to provide a thin type camera module comprises an image-sensing semiconductor assembly with a COF wiring film. The COF wiring film possesses all circuit design including module circuit for the thin type camera module to integrate a module circuit of the thin type camera module in the image-sensing semiconductor assembly so that an extra circuit substrate is not necessary. The COF wiring film with module circuit has input/output terminals directly to let image-sensing semiconductor assembly enables mounting of passive element. The image-sensing semiconductor assembly could be connected to a fixing board or a lens holder firstly for variedly process flow.  
       [0008] According to the thin type camera module of the present invention, which comprises a fixing board, an image-sensing semiconductor assembly and a lens holder. The image-sensing semiconductor assembly comprises a COF wiring film and an image sensing chip. The the COF wiring film forms a plurality of connecting ends around a window of the COF wiring film for flip-chip connecting. The connecting ends is disposed on a surface of the COF wiring film. The image sensing chip has a photosensitive surface with a plurality of bumps. The image sensing chip is flip-chip mounted to the COF wiring film by electrically connecting the bumps and the connecting ends, and the photosensitive surface of the image sensing chip is corresponding to the window of the COF wiring film. Preferably, the COF wiring film includes a module circuit for connecting passive element what the thin type camera module need. The lens holder is mounted on the fixing board to form an airtight space. The image sensing chip locates inside the airtight space and the photosensitive surface of the image sensing chip is toward a light-pervious channel of the lens holder for capturing image. 
     
    
    
     DESCRIPTION OF THE DRAWINGS  
     [0009]FIG. 1 is a cross-sectional view illustrating a thin type camera module of a first embodiment of the present invention.  
     [0010]FIG. 2 is a cross-sectional view illustrating an image-sensing semiconductor assembly of the thin type camera module of the first embodiment of the present invention.  
     [0011]FIG. 3 is a process flow chart of the thin type camera module of the first embodiment of the present invention.  
     [0012]FIG. 4 is a cross-sectional view illustrating a thin type camera module of a second embodiment of the present invention.  
     [0013]FIG. 5 is a cross-sectional view illustrating an image-sensing semiconductor assembly of the thin type camera module of the second embodiment of the present invention. 
    
    
     DEATAILED DESCRIPTION OF THE PRESENT INVENTION  
     [0014] Referring to the drawings attached, the present invention will be described by means of the embodiments below.  
     [0015] As showed in FIG. 1, a thin type camera module  100  of a first embodiment of the present invention comprises a fixing board  110 , a lens holder  120  and an imaging-sensing semiconductor assembly  130 , wherein the fixing board  110  is a kind of hard material without electrical transmitting function, such as BT substrate, FR-4 substrate, ceramic substrate or metal plate. The lens holder  120  is mounted on the fixing board  110  to form an airtight space to fix the imaging-sensing semiconductor assembly  130 . The lens holder  120  has a light-pervious channel  121  which forms a connecting portion  122 , such as inner thread of a screw, at a opening of the light-pervious channel  121  for connecting a camera lens  140 . The camera lens  140  has a lens  141  and its shape is like a cylindrical. The camera lens  140  is fixed or connected to the lens holder  120  in adjustable type.  
     [0016] Referring to FIGS. 1 and 2, the imaging-sensing semiconductor assembly  130  comprises a COF (chip-on film) wiring film  131  and an image sensing chip  134 , wherein the COF wiring film  131  is flexible, such as polyimide (PI). The COF wiring film  131  has a first surface  131   a , a second surface  131   b  and a window  132 . The window  132  is passing through the first surface  131   a  and the second surface  131   b . In this embodiment, the COF wiring film  131  has a plurality of metal wires forming on the first surface  131   a . The metal wires has a plurality of connecting ends  133  which are disposed around the window  132  on the first surface  131   a  of the COF wiring film  131 . The image sensing chip  134  is optical sensing chip, CCD (charge coupled device), CMOS (complementary metal oxide semiconductor) or photodiode, which is having a photosensitive surface  135 . A plurality of bumps  136 , such as gold bumps, are formed on peripherals of the photosensitive surface  135  for output terminals of the image sensing chip  134 . The image sensing chip  134  is flip-chip mounted on the COF wiring film  131 , and its photosensitive surface  135  is corresponding to the window  132  and the bumps  136  are electrically connected with the connecting ends  133 . Preferably, a sealant layer  137 , such as ACF (anisotropic conductive film), NCF (non-conductive film), UV past or thermosetting filling past, is disposed around the window  132  of the COF wiring film  131  between the first surface  131   a  of the COF wiring film  131  and the photosensitive surface  135  of the image sensing chip  134 . The sealant layer  137  encloses the bumps  136  of the image sensing chip  134  and combines the COF wiring film  131  with the image sensing chip  134  for improving reliability of electrically connecting of the connecting ends  133  and the bumps  136 .  
     [0017] The image sensing chip  134  is disposed inside the airtight space which is formed by the lens holder  120  and the fixing board  110 . Inside the airtight space, it can be vacuum state or inert gas filled, such as Nitrogen or Argon gas, for avoiding moisture invading and effecting the image sensing chip  134  capturing image. In this embodiment, the fixing board  110  forms a recession  111 . The image sensing chip  134  is attaching on the recession by an adhesive layer  112  (such as past or tape) which is formed at bottom surface of the image sensing chip  134 . The recession  111  assists the image sensing chip  134  in locating for aligning with the photosensitive surface  135  and the light-pervious channel  121  of the lens holder  120 . Perfectly, the lens holder  120  disposes a filter  123  which is also aligning with the light-pervious channel  121  and corresponding to the photosensitive surface  135  of the image sensing chip  134 . The filter  123  is used for filtering out the infrared in order to avoid causing noise or false color. Besides, the COF wiring film  131  includes a module circuit  138  which is formed on extending surface which is not covered by the lens holder  120 . The module circuit  138  is electrically connecting at least an electric device  151 , such as a passive component (selected from resistant, inductance and capacitance) or a active component. A plurality of connection fingers  152  are connected with the module circuit  138  of the COF wiring film  131  and the image sensing chip  134 , which are used for input/output terminals of the whole thin type camera module  100  for electrically connecting to exterior electrical device.  
     [0018] The imaging-sensing semiconductor assembly  130  of the thin type camera module  100  of the present invention is manufactured by a Chip-On-Film (COF) packaging method. The thin type camera module is thinner and suited for continuously mass producing the image-sensing semiconductor assemblies to reduce the thin type camera module running cost. The image sensing chip  134  is flip-chip mounted on the COF wiring film  131 . The connecting ends  133  of the COF wiring film  131 , which are disposed surrounding the window  132  on the first surface  131   a  for better stability of the image sensing chip  134 . And, the fixing board  110  forms the recession  111  for installing the image sensing chip  134  and achieve forming a thinner thin type camera module  100 . In addition, the COF wiring film  131  of imaging-sensing semiconductor assembly  130  can provide all circuit design of the thin type camera module  100  to integrating the module circuit  138  of the image-sensing semiconductor assembly  130 . And the COF wiring film  131  is formed input/output terminals directly, so the hard circuit substrate is not necessary. The COF wiring film  131  with the module circuit  138 , which is flexible and exposing out of the lens holder  120 , so process flow of the thin type of camera module  100  is various. The image-sensing semiconductor assembly  130  could be connected to the fixing board  110  or the lens holder  120  at first base on process flow design to achieve elastic process flow because that the image-sensing semiconductor assembly  130  is not necessary to electrically connect to the lens holder  120  and the fixing board  110 .  
     [0019] One of manufacturing process flows for the thin type camera module  100  of above description is shown in FIG. 3. The detailed description of the process flow of the thin type camera module  100  is as following:  
     [0020] Firstly, a COF tape is provided in a step  11  of “providing a COF tape”. The COF tape is rolled in the reel, which comprises a plurality of mentioned-above COF wiring films  131 . Each first surface  131   a  of the COF wiring film  131  forms a plurality of metal wires which include a plurality of connecting ends  133  disposed around the window  132  on the first surface  131   a . Preferably, the metal wires are connecting with the module circuit  138 .  
     [0021] Then, the imaging-sensing semiconductor assembly  130  is manufactured by a COF packaging method in a step  12  of “manufacturing an imaging-sensing semiconductor assembly from the COF tape”. Peripherals of the photosensitive surface  135  of the image sensing chip  134  are a plurality bumps  136  which are non-reflowable conductive bumps such as gold, copper, aluminum or its alloy, or solder bumps. In this embodiment, the bumps  136  are gold bumps for flip-chip mounted to the COF tape. Then, he image sensing chips  134  are flip-chip mounted to the COF tape. Preferably, prior to the flip-chip mounting step, a sealant layer  137  such as an ACF or a NCF is coated. The photosensitive surface  135  of the image sensing chip  134  is corresponding the window  132  and face down, and the face surface  131   a  of the COF wiring film  131  is face up for flip-chip mounting the image sensing chip  134  on the COF wiring film  131 . In one embodiment, the sealant layer  137  is an ACF, the bumps  136  could not be necessary to bond with the connecting ends  133  actually. The bumps  136  are electrically connected to the connecting ends  133  vertically by conductive particles of the ACF sealant layer  137 . The sealant layer  137  encloses the bumps  136  for protecting the bumps and improving reliability of electrically connecting of the connecting ends  133  and the bumps  136 . Perfectly, at least an electric device  151  is surface-mounted to the module circuit  138  of the COF wiring film  131  for constututing whole module circuit  138  and electrical functions in the imaging-sensing semiconductor assembly  130 . So the COF tape can package the pluralities of image-sensing semiconductor assemblies  130  continuously, then the COF tape is singulated to get image-sensing semiconductor assemblies  130  for next step of process flow of the thin type camera module  100 .  
     [0022] Then, the image-sensing semiconductor assembly  130  is fixed to the fixing board  110  in a step  13  “mechanically connecting the image-sensing semiconductor assembly to a fixing board”. The fixing board  110  has a recession  111 . The adhesive layer  112  is prepared in the recession  111  for adhering the image sensing chip  134 . The recession  111  assists the image sensing chip  134  in fixing the image sensing chip  134  and the capturing angle in position, meanwhile, providing a thinner module.  
     [0023] Then, the lens holder  120  is connecting to the fixing board  110  to form an airtight space in a step  14  of “mechanically connecting a lens holder to the fixing board”. The image sensing chip  134  is located inside the airtight space for avoiding dust invading it. The lens holder  120  has a light-pervious channel  121  which is connecting a camera lens  140  at a opening of the light-pervious channel  121 . Preferably, the lens holder  120  includes a filter  123  which is aligning with the light-pervious channel  121 . The photosensitive surface  135  of the image sensing chip  134 , the filter  123  of the lens holder  120  and the lens  141  of the camera lens  140  are forming on the light-pervious channel  121  and corresponding each other for capturing image. In the process flow of the thin type camera module  100  of above description, the image-sensing semiconductor assembly  130  is located on the fixing board  110  and the recession  111  of the fixing board  110  assists the image sensing chip  134  in locating for the photosensitive surface  135  of the image sensing chip  134  corresponding to the filter  123  and lens  141  in order to align correctly and get right capturing angle.  
     [0024] As showed in FIG. 4, a thin type camera module  200  of a second embodiment of the present invention comprises a fixing board  210 , a lens holder  220  and an imaging-sensing semiconductor assembly  230 , wherein the fixing board  210  is a kind of hard substrate without electrical function. The lens holder  220  is mounted on the fixing board  210  to form an airtight space. The lens holder  220  has a light-pervious channel  221  which forms a connecting portion  222  for connecting a camera lens  240 . The imaging-sensing semiconductor assembly  230  comprises a COF wiring film  231  and an image sensing chip  134 . The image sensing chip  134  is disposed insides the airtight space. The COF wiring film  231  has a first surface  231   a , a second surface  231   b , a window  232  which passes through the first surface  231   a  and the second surface  231   b , and at least a conductive via  239  disposed around the window  232 . In this embodiment, the COF wiring film  231  has a plurality of metal wires forming on the second surface  231   b . The metal wires includes a plurality of connecting ends  233  disposed on the first surface  231   a  around the window  232 . The conductive vias  239  electrically connect the connecting ends  233 . Surrounding the photosensitive surface  235  of the image sensing chip  234  are a plurality of bumps  236 . In this embodiment, the bumps  236  are reflowable solder bumps. FIG. 5 is a cross-section view illustrating of the imaging-sensing semiconductor assembly  230  after manufactured by a chip-on-film packaging method. The photosensitive surface  235  of the image sensing chip  234  is face-down and corresponding to the window  232  of the COF wiring film  231  during flip-chip mounting step. The first surface  231   a  of the COF wiring film  231  is face-up and the image sensing chip  234  is flip-chip mounted on the COF wiring film  231 . The bumps  236  electrically connect the connecting ends  233 . Preferably, a sealant layer  237  is formed surrounding the windows  232  of the COF wiring film  231  after flip-chip mounting. In this embodiment, the sealant layer  237  is a thermosetting compound such as UV past, transparent thermosetting liquid compoundt or underfilling material. The sealant layer  237  fills the surrounding of the photosensitive surface  235  of the image sensing chip  234  by capillarity, but it is not covering the active area of the photosensitive surface  235 . The sealant layer  237  encloses the bumps  236  for fixing the image sensing chip  234  and the COF wiring film  231  and for improving reliability of electrically connecting of the connecting ends  233  and the bumps  236 .  
     [0025] In this embodiment, thickness of the image sensing chip  234  is thinner by grinding bottom surface of the image sensing chip  234  for providing a thinner module and a better horizontal plane corresponding to the photosensitive surface  235 . When the image sensing chip  234  of the imaging-sensing semiconductor assembly  230  is disposed inside the airtight space which is formed by the lens holder  220  and the fixing board  210 , an adhesive layer  211  (such as past or tape) is formed between the bottom surface of the image sensing chip  234  and the fixing board  210  for fixing the image sensing chip  234  on the fixing board  210 . The image sensing chip  234  is steadier and having a steady capturing angle. The photosensitive surface  235  of image sensing chip  234  is aligning with the light-pervious channel  221  of the lens holder  220 . The lens holder  220  comprises a filter  223  which is also aligning with the light-pervious channel  221  and corresponding to the photosensitive surface  235  of the image sensing chip  234 . The photosensitive surface  235  of the image sensing chip  234 , the filter  223  of the lens holder  220  and the lens  241  of the camera lens  240  are forming in the light-pervious channel  221  and corresponding each other for capturing image. In addition, the metal wires of the COF wiring film  231  includes a module circuit  238  for electrically mounting at least a passive component  251  of the thin type camera module  200  in the imaging-sensing semiconductor assembly  230 . The module circuit  238  is formed on an extended surface of the fixing board  210  which is not covered by the lens holder  220  for electrically connecting the electric device  251 . Connection fingers  252  are connected with the module circuit  238  of the COF wiring film  231  and the image sensing chip  234 , which are used for input/output terminals of the whole thin type camera module  200 .  
     [0026] Therefore, thickness of the thin type camera module  200  is thinner. The imaging-sensing semiconductor assembly  230  of the thin type camera module  200  is suited for continuously mass production to reduce the thin type camera module running cost.  
     [0027] The whole circuit patterns of the thin type camera module  200  are integrated in the imaging-sensing semiconductor assembly  230  with module circuit  238 , so the extra module substrate is not necessary. The COF wiring film  231  with module circuit  238  is flexible and partially exposed out of the lens holder  220 . The image-sensing semiconductor assembly  230  could be mechanically connected to the fixing board  210  or the lens holder  220  elastically for varieous process flow of the thin type camera module  200 .  
     [0028] The above description of embodiments of this invention is intended to be illustrated and not limiting. Other embodiments of this invention will be obvious to those skilled in the art in view of the above disclosure.