Abstract:
The present invention discloses a method for assembling a camera module. The method includes putting plural conductive bumps on a conductive contact of a substrate such that a large conductive bump is formed, and pressing the substrate and an image chip together such that the conductive contact contacts with a pad formed on the image chip through the large conductive bump to combine the conductive contact and the pad. Since there is no contact between the substrate and the image chip but the large conductive bump, the method decreases the probability for fracture between the substrate and the image chip and improves the quality of the camera module.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention generally relates to a method for assembling a camera module, and more particularly to an assembling method for applying to a camera module on a portable electronic device such as a cell phone or a personal digital assistant (PDA). 
       DESCRIPTION OF THE RELATED ART 
       [0002]    A conventional camera module is assembled by a Flip-Chip package technology, and an assembling process thereof is described hereinafter first. Referring to  FIG. 1 , a flow chart of a conventional method for assembling a camera module is illustrated therein. A method for assembling the conventional camera module comprises a step S 1 : providing a ceramic substrate; a step  2 : putting a conductive bump on an image chip; a step  3 : pressing the ceramic substrate and the image chip together, so as to connect the conductive bump with a conductive contact; step  4 : filling a sealing glue between the ceramic substrate and the image chip; and a step  5  finally: fixing a lens module on the ceramic substrate by an adhesive. 
         [0003]    Each of the steps of the method for assembling the conventional camera module is illustrated above, and then referring to  FIGS. 2A ,  2 B,  2 C and  2 D, schematic views of a conventional method for assembling a camera module are illustrated therein. According to the  FIG. 2A , the ceramic substrate  11  has a conductive contact  111  and an aperture  112 . The image chip  12  comprises a sensing region  121  and a pad  122 , and a conductive bump  13  is disposed on the pad  122  as illustrated in the step S 2 . In general, the conductive bump  13  is made of aurum (Au).  FIG. 2B  illustrates the ceramic substrate  11  and the image chip  12  being pressed together, wherein the conductive bump  13  and the conductive contact  111  are connected with one another.  FIG. 2C  illustrates a sealing glue  14  being filled between the ceramic substrate  11  and the image chip  12 .  FIG. 2D  illustrates a lens module  16  being fixed on the ceramic substrate  11  and thus a camera module  1  is formed. 
         [0004]    Functions of components in the camera module  1  are described hereinafter in detail with  FIG. 2D . The conductive contact  111  of the ceramic substrate  11  is electrically connected with the pad  122  of the image chip  12  via the conductive bump  13 , and thus the camera module  1  is able to be conducted and activated. The sealing glue  14  is used for sealing the ceramic substrate  11  and the image chip  12  to avoid the camera module  1  being damaged by dust and mist. The camera module  16  comprises a lens  161  and a lens holder  162 . The lens  161  is aligned to the aperture  112  and the sensing region  121 , and thus light passing through the lens  161  and the aperture  112  is received by the sensing region  121  to generate an image when the camera module  1  is operated, wherein the lens module  16  is fixed on the ceramic substrate  11  by an adhesive. 
         [0005]    The conventional camera module may be manufactured by the above-mentioned assembling process. However, the aperture  112  is formed by using a perforating element to punch the ceramic substrate  11  during a process for forming the aperture  112  of the ceramic substrate  11 . A burr  113  is formed on an edge of the aperture  112  as illustrated in  FIGS. 2A˜2D  after the perforating element perforates the ceramic substrate  11  and is pulled out of the aperture  112 . Thus, where the burr  113  of the ceramic substrate  11  contacts the image chip  12  is formed as a pivot when the ceramic substrate  11  and the image chip  12  are pressed together. However, an extra force acting on the pivot (the burr  113 ) is likely to form a moment about the camera module  1  when the burr  113  is formed as the pivot. The moment may fracture a conjunction between the conductive bump  13  and the conductive contact  111 , and thus the ceramic substrate  11  and the image chip  12  are likely to be separated from one another due to an instable connection therebetween. Besides, the substrate may have an uneven surface due to various factors during manufacturing process, such as manufacture tolerance. Where the uneven surface contacts the image chip  12  is also likely to form as a pivot, so as to fracture the conjunction between the conductive bump and the conductive contact. Thus, it is important to provide a camera module with more stable structure and thus with higher quality. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention is directed to a method for assembling a camera module with more stable structure. 
         [0007]    In a prefer embodiment, the present invention provides a method for assembling a camera module comprising the following steps. A first conductive bump is put on a conductive contact of a substrate. A second conductive bump is put on the first conductive bump to form a large conductive bump. The large conductive bump is flattened, and thus a top of the large conductive bump is pressed to form a top plane. The substrate and an image chip are pressed together to combine the large conductive bump and a pad on the image chip, and thus the conductive contact is electrically connected with the pad. Further, a sealing glue is filled between the substrate and the image chip. 
         [0008]    According to a prefer embodiment, the method for assembling the camera module of the present invention further comprises a step of fixing a lens module on the substrate, wherein the lens module comprises a lens holder and a lens, and the lens is aligned to a sensing region of the image chip. 
         [0009]    According to a prefer embodiment, the large conductive bump is flattened by a pressing head to form the top plane. 
         [0010]    According to a prefer embodiment, the method for assembling the camera module of the present invention further comprises a step of putting a third conductive bump on the pad of the image chip before pressing the substrate and the image chip together. 
         [0011]    According to a prefer embodiment, when the substrate and the image chip are pressed together, the third conductive bump is aligned to and contacts with the top plane, and thus the third conductive bump is electrically connected with the large conductive bump due to the conjunction therebetween, and accordingly the conductive contact is electrically connected with the pad. 
         [0012]    According to a prefer embodiment, the substrate is a rigid-flex printed circuit board, a copper foil substrate (FR4 substrate) or a ceramic substrate. 
         [0013]    According to a prefer embodiment, the rigid-flex printed circuit board comprises a first hard circuit board, a second hard circuit board and a soft circuit board disposed between the first hard circuit board and the second hard circuit board, and the conductive contact is disposed on the first hard circuit board. 
         [0014]    In a prefer embodiment, the present invention further provides a method for assembling a camera module comprising the following steps. A first conductive bump and a second conductive bump are respectively put on a first conductive contact and a second conductive contact on a substrate. A third conductive bump is put on the first conductive bump to form a first large conductive bump, and a fourth conductive bump is put on the second conductive bump and a fifth conductive bump is put on the fourth conductive bump to form a second large conductive bump. The first large conductive bump and the second large conductive bump are flattened, and thus a first top of the first large conductive bump and a second top of the second large conductive bump are respectively pressed to form a first top plane and a second top plane. The substrate and an image chip are pressed together to combine the first large conductive bump and a first pad on the image chip and connect the second large conductive bump with a second pad on the image chip, and thus the first conductive contact is electrically connected with the first pad and the second conductive contact is electrically connected with the second pad. Further, a sealing glue is filled between the substrate and the image chip. 
         [0015]    According to a prefer embodiment, the method for assembling the camera module of the present invention further comprises a step of fixing a lens module on the substrate, wherein the lens module comprises a lens holder and a lens, and the lens is aligned to a sensing region of the image chip. 
         [0016]    According to a prefer embodiment, the first large conductive bump and the second large conductive bump are flattened by a pressing head to form the first top plane and the second top plane respectively. 
         [0017]    According to a prefer embodiment, the method for assembling the camera module of the present invention further comprises a step of respectively putting a sixth conductive bump and a seventh conductive bump on the first pad and the second pad of the image chip before pressing the substrate and the image chip together. 
         [0018]    According to a prefer embodiment, when the substrate and the image chip are pressed together, the sixth conductive bump is aligned to and contacts with the first top plane and the seventh conductive bump is aligned to and contacts with the second top plane, and thus the sixth conductive bump is electrically connected with the first large conductive bump due to the conjunction therebetween and the seventh conductive bump is electrically connected with the second large conductive bump due to the conjunction therebetween, and accordingly the first conductive contact is electrically connected with the first pad and the second conductive contact is electrically connected with the second pad. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]      FIG. 1  illustrates a flow chart of a conventional method for assembling a camera module. 
           [0020]      FIGS. 2A ,  2 B,  2 C and  2 D illustrate schematic views of a conventional method for assembling a camera module. 
           [0021]      FIG. 3  illustrates a flow chart of a method for assembling a camera module according to a first prefer embodiment of the present invention. 
           [0022]      FIGS. 4A ,  4 B,  4 C,  4 D,  4 E and  4 F illustrate schematic views of a method for assembling a camera module according to a first prefer embodiment of the present invention. 
           [0023]      FIG. 5  illustrates a flow chart of a method for assembling a camera module according to a second prefer embodiment of the present invention. 
           [0024]      FIGS. 6A ,  6 B,  6 C,  6 D,  6 E and  6 F illustrate schematic views of a method for assembling a camera module according to a second prefer embodiment of the present invention. 
           [0025]      FIG. 7  illustrates a flow chart of a method for assembling a camera module according to a third prefer embodiment of the present invention. 
           [0026]      FIGS. 8A ,  8 B,  8 C,  8 D,  8 E and  8 F illustrate schematic views of a method for assembling a camera module according to a third prefer embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0027]    Reference will now be made in detail to specific embodiments of the present invention. Examples of these embodiments are illustrated in the accompanying drawings. While the invention will be described in conjunction with these specific embodiments, it will be understood that it is not intended to limit the invention to these embodiments. In fact, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. In the following description, numerous specific details are set forth in order to provide a through understanding of the present invention. The present invention may be practiced without some or all of these specific details. In other instances, well-known process operations are not described in detail in order not to obscure the present invention. 
         [0028]    In view of the defects of the conventional method for assembling a camera module, the present invention provides a method for assembling a camera module with more stable structure. Referring to  FIG. 3 , a flow chart of a method for assembling a camera module according to a first prefer embodiment of the present invention is illustrated therein. The method for assembling a camera module of the present invention comprises the following steps. A step S 1 ′ is putting a first conductive bump on a conductive contact of a substrate. A step S 2 ′ is putting a second conductive bump on the first conductive bump to form a large conductive bump. A step S 3 ′ is flattening the large conductive bump, and thus a top of the large conductive bump is pressed to form a top plane. A step S 4 ′ is pressing the substrate and an image chip together to combine the large conductive bump and a pad on the image chip, and thus the conductive contact is electrically connected with the pad. A step S 5 ′ is filling a sealing glue between the substrate and the image chip. Further, a step S 6 ′ is fixing a lens module on the substrate. 
         [0029]    Referring to  FIGS. 4A ,  4 B,  4 C,  4 D,  4 E and  4 F hereinafter, schematic views of a method for assembling a camera module according to a first prefer embodiment of the present invention is illustrated therein. The substrate may use a rigid-flex printed circuit board, a copper foil substrate or a ceramic substrate. In the present prefer embodiment, the substrate is illustrated as a rigid-flex printed circuit board  21 . In  FIG. 4A , the rigid-flex printed circuit board  21  (i.e. substrate) comprises a first hard circuit board  211 , a second hard circuit board  212  and a soft circuit board  213  disposed between the first hard circuit board  211  and the second hard circuit board  212 , and the first hard circuit board  211  has a conductive contact  2111 . The rigid-flex printed circuit board  21  has an aperture  214  and a burr  215  formed by a process for forming the aperture  214 , wherein the aperture  214  passes through the first hard circuit board  211 , the second hard circuit board  212  and the soft circuit board  213 , and is located at a center of the rigid-flex printed circuit board  21 . The burr  215  has a highest surface  2151 , and a height of the highest surface  2151  is presented as a surface height Hs. A first conductive bump  23  is put on a conductive contact  2111  of the rigid-flex printed circuit board  21  (i.e. the step S 1 ′), and a height of the first conductive bump  23  is presented as a first height H 1 , and the first height H 1  is lower than the surface height Hs, wherein the surface height Hs and the first height H 1  are defined by measuring from a bottom of the rigid-flex printed circuit board  21 . 
         [0030]    Next, a second conductive bump  24  is put on the first conductive bump  23  to form a large conductive bump  23 ′ (i.e. the step S 2 ′). The large conductive bump  23 ′ has a top  231 ′, and a height of the top  231 ′ of the large conductive bump  23 ′ is presented as a second height H 2 , wherein the second height H 2  is higher than the surface height Hs. As illustrated in  FIG. 4A , the first height H 1  is lower than the surface height Hs, and thus the method of the present invention further puts the second conductive bump  24  on the first conductive bump  23 , so as to let the conductive bumps put on the conductive contact  2111  become higher than the surface height Hs. In the prefer embodiment, the first conductive bump  23  and the second conductive bump  24  are made of aurum. It should be noted that structures, shapes and heights of the rigid-flex printed circuit board  21  and the large conductive bump  23 ′ located at a left side of the aperture  214  are all the same as structures, shapes and heights of the rigid-flex printed circuit board  21  and the large conductive bump  23 ′ located at a right side of the aperture  214 . For simplifying the drawing, the height symbols are only marked on the rigid-flex printed circuit board  21  and the large conductive bump  23 ′ at the left side of the  FIG. 4A , and the element symbols are only marked on the rigid-flex printed circuit board  21  and the large conductive bump  23 ′ at the right side of the  FIG. 4A , so as to showing the symbols clearly instead of too complicate drawing. 
         [0031]    In  FIG. 4B , the large conductive bump  23 ′ is flattened by a pressing head  3 , so as to press the top  231 ′ of the large conductive bump  23 ′ to form a top plane  232 ′ (i.e. the step S 2 ′), and a height of the top plane  232 ′ is presented as a third height H 3 . The third height H 3  is lower than the second height H 2  but still higher than the surface height Hs, wherein the second height H 2  and the third height H 3  are also defined by measuring from the bottom of the rigid-flex printed circuit board  21 . Comparing  FIG. 4A  with  FIG. 4B , a contact area of the top  231 ′ is quite small due to the top  231 ′ is a spherical surface, but the top plane  232 ′ formed by flattening is a plane, and thus a contact area of the top plane  232 ′ is larger than that of the top  231 ′. 
         [0032]    In  FIG. 4C , an image chip  22  comprises a sensing region  221  and a pad  222 , and the pad  222  of the image chip  22  is aligned to the top plane  232 ′ of the large conductive bump  23 ′. Next, the rigid-flex printed circuit board  21  and the image chip  22  are pressed together to combine the large conductive bump  23 ′ and the pad  222  on the image chip  22 , and thus the conductive contact  2111  is electrically connected with the pad  222  as illustrated in  FIG. 4D  (i.e. the step S 4 ′). In  FIG. 4E , a sealing glue  26  is filled for avoiding dust and mist entering into where between the rigid-flex printed circuit board  21  and the image chip  22  (i.e. the step S 5 ′). In  FIG. 4F , a lens module  28  is fixed on the second hard circuit board  212  to form a camera module  2  (i.e. the step S 6 ′), wherein the lens module  28  comprises a lens holder  282  and a lens  281 , and the lens  281  is aligned to the sensing region  221  of the image chip  22 . In the prefer embodiment, the lens module  28  is fixed on the second hard circuit board  212  by an adhesive  27 . Structures and functions of each component of the camera module  2  are all the same as the conventional one and are omitted herein. It should be noted that the prefer embodiment illustrating the substrate as the rigid-flex printed circuit board  21  is for example only, the present invention may also be practiced by using a copper foil substrate or a ceramic substrate as the substrate without varying the assembling process. 
         [0033]    The method for assembling the camera module of the present invention is described above in detail. The characteristic of the present invention is disposing at least an additional conductive bump on the original conductive bump to ensure the total height of all conductive bumps is higher than the surface height of the highest surface whether the original conductive bump on the conductive contact is higher than the surface height or not. Accordingly, there is no pivot formed by the burr of the substrate contacting the image chip, and thus a moment about the camera module formed by an extra force acting on the pivot in the related art is not likely to form, so as to avoid fracturing the conjunction between the conductive bump and the conductive contact. 
         [0034]    In addition, the present invention further provides a second prefer embodiment as illustrated in  FIG. 5 , a flow chart of a method for assembling a camera module according to a second prefer embodiment of the present invention is illustrated therein. The method for assembling a camera module of the present invention comprises the following steps. A step S 1 ″ is putting a first conductive bump on a conductive contact of a substrate. A step S 2 ″ is putting a second conductive bump on the first conductive bump to form a large conductive bump. A step S 3 ″ is putting a third conductive bump on a pad of an image chip. A step S 4 ″ is flattening the large conductive bump, and thus a top of the large conductive bump is pressed to form a top plane. A step S 5 ″ is pressing the substrate and the image chip together to combine the large conductive bump and the third conductive bump, and thus the conductive contact is electrically connected with the pad. A step S 6 ″ is filling a sealing glue between the substrate and the image chip. Further, a step S 7 ″ is fixing a lens module on the substrate. 
         [0035]    Referring to  FIGS. 6A ,  6 B,  6 C,  6 D,  6 E and  6 F hereinafter, schematic views of a method for assembling a camera module according to a second prefer embodiment of the present invention is illustrated therein. In the prefer embodiment, the substrate is illustrated as a ceramic substrate  41 . In  FIG. 6A , the ceramic substrate  41  (i.e. substrate) comprises a conductive contact  411 , an aperture  412  and a burr  413 . The aperture  412  passes through the ceramic substrate  41  and is located at a center of the ceramic substrate  41 . The burr  413  has a highest surface  4131 , and a height of the highest surface  4131  is presented as a surface height Hs′. In addition, an image chip  42  comprises a sensing region  421  and a pad  422 . A first conductive bump  43  is put on a conductive contact  411  of the ceramic substrate  41  (i.e. the step S 1 ″), and a third conductive bump  45  is put on the pad  422  of the image chip  42  (i.e. the step S 3 ″). A height of the first conductive bump  43  is presented as a first height H 1 ′, and the first height H 1 ′ is lower than the surface height Hs′, wherein the surface height Hs′ and the first height H 1 ′ are defined by measuring from a bottom of the ceramic substrate  41 . 
         [0036]    Next, a second conductive bump  44  is put on the first conductive bump  43  to form a large conductive bump  43 ′ (i.e. the step S 2 ″). The large conductive bump  43 ′ has a top  431 ′, and a height of the top  431 ′ of the large conductive bump  43 ′ is presented as a second height H 2 ′, wherein the second height H 2 ′ is higher than the surface height Hs′. As illustrated in  FIG. 6A , the first height H 1 ′ is lower than the surface height Hs′, and thus the method of the present invention further puts the second conductive bump  44  on the first conductive bump  43 , so as to let the conductive bumps put on the conductive contact  411  become higher than the surface height Hs′. In the prefer embodiment, the first conductive bump  43 , the second conductive bump  44  and the third conductive bump  45  are made of aurum. It should be noted that the present prefer embodiment is similar to the first prefer embodiment, i.e. structures, shapes and heights of the ceramic substrate  41  and the large conductive bump  43 ′ located at two sides of the aperture  412  are all the same. Therefore, for simplifying the drawing, the height symbols are only marked on the ceramic substrate  41  and the large conductive bump  43 ′ at the left side of the  FIG. 6A , and the element symbols are only marked on the ceramic substrate  41  and the large conductive bump  43 ′ at the right side of the  FIG. 6A , so as to showing the symbols clearly instead of too complicate drawing. 
         [0037]    In  FIG. 6B , the large conductive bump  43 ′ is flattened by a pressing head  5 , so as to press the top  431 ′ of the large conductive bump  43 ′ to form a top plane  432 ′ (i.e. the step S 4 ″), and a height of the top plane  432 ′ is presented as a third height H 3 ′. The third height H 3 ′ is lower than the second height H 2 ′ but still higher than the surface height Hs′, wherein the second height H 2 ′ and the third height H 3 ′ are also defined by measuring from the bottom of the ceramic substrate  41 . In the step S 3 ″, the top  431 ′ of the large conductive bump  43 ′ is transformed from a spherical surface into the top plane  432 ′, so as to let the large conductive bump  43 ′ have a larger contact area. 
         [0038]    In  FIG. 6C , the pad  422  of the image chip  42  is aligned to the top plane  432 ′ of the large conductive bump  43 ′. Thereafter, the ceramic substrate  41  and the image chip  42  are pressed together to combine the large conductive bump  43 ′ and the third conductive bump  45 , and thus the conductive contact  411  is electrically connected with the pad  422  as illustrated in  FIG. 6D  (i.e. the step S 5 ″). In  FIG. 6E , a sealing glue  46  is filled for avoiding dust and mist entering into where between the ceramic substrate  41  and the image chip  42  (i.e. the step S 6 ″). In  FIG. 6F , a lens module  48  is fixed on the ceramic substrate  41  to form a camera module  4  (i.e. the step S 7 ″), wherein the lens module  48  comprises a lens holder  482  and a lens  481 , and the lens  481  is aligned to the sensing region  421  of the image chip  42 . In the prefer embodiment, the lens module  48  is fixed on the ceramic substrate  41  by an adhesive  27 . Structures and functions of each component of the camera module  4  are all the same as the conventional one and are omitted herein. 
         [0039]    The method for assembling the camera module of the present invention is described above in detail. In the prefer embodiment, another additional conductive bump is disposed on the image chip. Therefore, a conjunction between the conductive contact and the pad is reinforced due to combining the large conductive bump and the additional conductive bump when the ceramic substrate and the image chip are pressed together, and thus a conjunction between the ceramic substrate and the image chip becomes more stable. It should be noted that for one, the prefer embodiment illustrating the substrate as the ceramic substrate  41  is for example only, the present invention may also be practiced by using a copper foil substrate or a rigid-flex printed circuit board as the substrate without varying the assembling process. For two, the method for assembling the camera module of the present invention does not limit to process the steps S 1 ″, S 2 ″ and S 3 ″ in sequence or simultaneously, i.e. the steps S 1 ″ and S 3 ″ may be processed simultaneously, the step S 1 ″ may be processed before the step S 3 ″, or the step S 1 ″ may be processed after the step S 3 ″. Also, the steps S 2 ″ and S 3 ″ may be processed simultaneously, the step S 2 ″ may be processed before the step S 3 ″, or the step S 2 ″ may be processed after the step S 3 ″. 
         [0040]    Besides, the present invention further provides a third prefer embodiment as illustrated in  FIG. 7 , a flow chart of a method for assembling a camera module according to a third prefer embodiment of the present invention is illustrated therein. The method for assembling a camera module of the present invention comprises the following steps. A step S 1 * is respectively putting a first conductive bump and a second conductive bump on a first conductive contact and a second conductive contact on a substrate. A step S 2 * is putting a third conductive bump on the first conductive bump to form a first large conductive bump, and putting a fourth conductive bump on the second conductive bump and putting a fifth conductive bump on the fourth conductive bump to form a second large conductive bump. A step S 3 * is respectively putting a sixth conductive bump and a seventh conductive bump on a first pad and a second pad of an image chip. A step S 4 * is flattening the first large conductive bump and the second large conductive bump, and thus a first top of the first large conductive bump and a second top of the second large conductive bump are respectively pressed to form a first top plane and a second top plane. A step S 5 * is pressing the substrate and the image chip together to combine the first large conductive bump and the first pad on the image chip and connect the second large conductive bump with the second pad on the image chip, and thus the first conductive contact is electrically connected with the first pad and the second conductive contact is electrically connected with the second pad. A step S 6 * is filling a sealing glue between the substrate and the image chip. Further, a step S 7 * is fixing a lens module on the substrate. 
         [0041]    Referring to  FIGS. 8A ,  8 B,  8 C,  8 D,  8 E and  8 F hereinafter, schematic views of a method for assembling a camera module according to a third prefer embodiment of the present invention is illustrated therein. In the prefer embodiment, the substrate is illustrated as a copper foil substrate  61 . In  FIG. 8A , the copper foil substrate  61  (i.e. substrate) comprises a first conductive contact  611 , a second conductive contact  612 , an aperture  613  and a burr  614 . A height of the first conductive contact  611  is presented as a first surface height Hs 1 *. A height of the second conductive contact  612  is presented as a second surface height Hs 2 *. The aperture  613  passes through the copper foil substrate  61  and is located at a center of the copper foil substrate  61 . The burr  614  has a highest surface  6141 , and a height of the highest surface  6141  is presented as a third surface height Hs 3 *. Since the first surface height Hs 1 * is higher than the second surface height Hs 2 *, the surface of the copper foil substrate  61  is uneven. In addition, an image chip  62  comprises a sensing region  621 , a first pad  622  and a second pad  623 . A first conductive bump  63  and a second conductive bump  64  are respectively put on the first conductive contact  611  and the second conductive contact  612  of the copper foil substrate  61  (i.e. the step S 1 *), wherein a height of the first conductive bump  63  is presented as a first height H 1 *, and a height of the second conductive bump  64  is presented as a second height H 2 *. As illustrated in  FIG. 8A , the second height H 2 * is lower than the first height H 1 *, and the first height H 1 * is lower than the third surface height Hs 3 *. 
         [0042]    Next, a third conductive bump  65  is put on the first conductive bump  63  to form a first large conductive bump  63 ′, and a fourth conductive bump  66  is put on the second conductive bump  64  and a fifth conductive bump  67  is put on the fourth conductive bump  66  to form a second large conductive bump  64 ′ (i.e. the step S 2 *). As illustrated in  FIG. 8A , a height of a first top  631 ′ of the first large conductive bump  63 ′ is presented as a third height H 3 *, and a height of a second top  641 ′ of the second large conductive bump  64 ′ is presented as a fourth height H 4 *, wherein the fourth height H 4 * is higher than the third height H 3 *, and the third height H 3 * is higher than the third surface height Hs 3 *, i.e. the first large conductive bump  63 ′ and the second large conductive bump  64 ′ are both higher than the highest surface  6141  of the burr  614 . Further, a sixth conductive bump  68  and a seventh conductive bump  69  are respectively put on the first pad  622  and the second pad  623  of the image chip  62  (i.e. the step S 3 *). In the prefer embodiment, the first conductive bump  63 , the second conductive bump  64 , the third conductive bump  65 , the fourth conductive bump  66 , the fifth conductive bump  67 , the sixth conductive bump  68  and the seventh conductive bump  69  are all made of aurum. 
         [0043]    In  FIG. 8B , the first large conductive bump  63 ′ and the second large conductive bump  64 ′ are flattened by a pressing head  7 , so as to press the first top  631 ′ of the first large conductive bump  63 ′ to form a first top plane  632 ′, and press the second top  641 ′ of the second large conductive bump  64 ′ to form a second top plane  642 ′ (i.e. the step S 4 *), wherein heights of the first top plane  632 ′ and the second top plane  642 ′ are equal to one another and both presented as a fifth height H 5 *. The fifth height H 5 * is lower than the third height H 3 * but still higher than the third surface height Hs 3 *. As illustrated in  FIG. 8A  and  FIG. 8B , the first height H 1 *, the second height H 2 *, the third height H 3 *, the fourth height H 4 *, the fifth height H 5 *, the first surface height Hs 1 *, the second surface height Hs 2 * and the third surface height are all defined by measuring from a bottom of the copper foil substrate  61 . 
         [0044]    In  FIG. 8C , the sixth conductive bump  68  and the seventh conductive bump  69  on the image chip  62  are respectively aligned to the first top plane  632 ′ of the first large conductive bump  63 ′ and the second top plane  642 ′ of the second large conductive bump  64 ′. Next, the copper foil substrate  61  and the image chip  62  are pressed together to respectively combine the first large conductive bump  63 ′ with the sixth conductive bump  68  and the second large conductive bump  64 ′ with the seventh conductive bump  69 , and thus the first conductive contact  611  and the second conductive contact  612  are respectively electrically connected with the first pad  622  and the second pad  623  as illustrated in  FIG. 8D  (i.e. the step S 5 *). In  FIG. 8E , a sealing glue  81  is filled for avoiding dust and mist entering into where between the copper foil substrate  61  and the image chip  62  (i.e. the step S 6 *). In  FIG. 8F , a lens module  82  is fixed on the copper foil substrate  61  to form a camera module  6  (i.e. the step S 7 *), wherein the lens module  82  comprises a lens holder  822  and a lens  821 , and the lens  821  is aligned to the sensing region  621  of the image chip  62 . In the prefer embodiment, the lens module  82  is fixed on the copper foil substrate  61  by an adhesive  83 . Structures and functions of each component of the camera module  6  are all the same as the conventional one and are omitted herein. 
         [0045]    It should be noted that for one, the prefer embodiment illustrating the substrate as the copper foil substrate  61  is for example only, the present invention may also be practiced by using a ceramic substrate or a rigid-flex printed circuit board as the substrate without varying the assembling process. For two, the method for assembling the camera module of the present invention does not limit to process the steps S 1 *, S 2 * and S 3 * in sequence or simultaneously, i.e. the steps S 1 * and S 3 * may be processed simultaneously, the step S 1 * may be processed before the step S 3 *, or the step S 1 * may be processed after the step S 3 *. Also, the steps S 2 * and S 3 * may be processed simultaneously, the step S 2 * may be processed before the step S 3 *, or the step S 2 * may be processed after the step S 3 *. 
         [0046]    According to the above-mentioned prefer embodiments, the characteristic of the present invention is contacting the conductive contact with the pad as better as possible when the substrate is combined with the image chip, so as to avoid other contact forming between the substrate and the image chip beside the contact of the conductive contact and the pad. Since the substrate is unavoidable to have an uneven surface, besides the original conductive bump put on the conductive contact, the present invention may further dispose at least an additional conductive bump on the original conductive bump to ensure the total height of all conductive bumps on the conductive contact is higher than the highest surface of the substrate, and thus the stability of the camera module is enhanced due to the possibility of the substrate contacting the image chip with any other portion besides the conductive contact is reduced. According to the reliability test, the camera module assembled by the method of the present invention certainly has a stronger structure than that assembled by the conventional method. Moreover, the present invention further comprises a step of flattening the large conductive bump to form the top plane on the conductive bump. Therefore, the alignment between the image chip and the substrate is easier due to the contact surface of the large conductive bump is enlarged, so as to avoid mismatching the image chip and the substrate. 
         [0047]    Although specific embodiments of the present invention have been described, it will be understood by those of skill in the art that there are other embodiments that are equivalent to the described embodiments. Accordingly, it is to be understood that the invention is not to be limited by the specific illustrated embodiments, but only by the scope of the appended claims.