Abstract:
An camera module includes a substrate, an image sensor chip, and a lens module. The image sensor chip is disposed on and electrically connected to the substrate. The lens module is mounted on the base via an adhesive layer. The lens module includes a bottom surface contacting with the substrate. The bottom surface defines at least one sloped surfaces thereon. At least one gap is defined between the substrate and the at least one sloped surface. The adhesive layer is disposed between the bottom surface and the substrate, the gap is capable of accepting adhesive when the lens module and substrate are pressed together.

Description:
BACKGROUND 
     1. Technical Field 
     The disclosure relates to a camera module. 
     2. Description of the Related Art 
     Current camera modules typically include an image sensor chip, a substrate, a number of gold wires, an encapsulation glass, and a lens module. The image sensor chip is disposed on the substrate and electrically connected to the substrate via the gold wires. The encapsulation glass encapsulates the image sensor chip and the gold wires. The lens module is installed on the substrate via adhesive layer, enclosing the image sensor chip, the gold wires, and the encapsulation glass. The problem is, during installing the lens module to the substrate, the adhesive layer is pressed and it spreads to the immediate area of the lens module on the substrate, contaminating the substrate. In addition, the adhered area of the lens module is limited to the bottom surface thereof, which is typically not adequate to provide reliable long term adherence. 
     What is desired is a camera module that can overcome the above-described problems. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present camera module is better understood with reference to the accompanying drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the camera module. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
         FIG. 1  is a schematic, cross-sectional view of a camera module, according to a first exemplary embodiment. 
         FIG. 2  is a schematic, cross-sectional view of a camera module, according to a second exemplary embodiment. 
         FIG. 3  is a schematic, cross-sectional view of a camera module, according to a third exemplary embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present camera module will now be described in detail with references to the drawings. 
     Referring to  FIG. 1 , a camera module  100 , according to a first exemplary embodiment, includes an image sensor chip  10 , a substrate  20 , an adhesive layer  30 , a number of conductive wires  35 , a lens module  40 , and a transparent cover  50 . 
     The image sensor chip  10  can be a charged coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS). The image sensor chip  10  includes a top surface  11  and a bottom surface  13  facing away from the top surface  11 . The image sensor chip  10  has a photosensitive area  12  formed on the center of the top surface  11 , and a non-photosensitive area  14  surrounding the photosensitive area  12 . The non-photosensitive area  14  has a number of chip pads  101  formed thereon. 
     The substrate  20  can be made of a material such as: polyimide, ceramic, or glass fiber. The substrate  20  has a supporting surface  22 . The bottom surface  13  of the image sensor chip  10  is adhered to the supporting surface  22  via the adhesive layer  30 . The adhesive layer  30  can be made, for example, from silicone, epoxy, acrylic, or polyamide. 
     A number of base pads  201  are disposed on the supporting surface  22  of the substrate  20 . Each base pad  201  can be electrically connected to a corresponding chip pad  101  via a conductive wire  35 . The conductive wires  35  can be made of a conductive material, such as gold, silver, aluminum, or an alloy thereof. 
     Alternatively, the image sensor chip  10  may be mechanically and electrically connected to the substrate  20  by available package processes, such as, chip-scale, wafer-level chip-scale, ceramic leaded, plastic leadless chip, thermal compression bonding, and flip chip packaging processes. 
     The lens module  40  is aligned with the image sensor chip  10 . The lens module  40  includes a lens barrel  42 , a lens holder  44 , and lens group  46 . The lens holder  44  comprises a top hollow cylinder  441 , a bottom hollow cylinder  442  coaxially aligned with and communicated with the top hollow cylinder  441 , and a connecting plate  443  connecting the top hollow cylinder  441  and the bottom hollow cylinder  442 . The lens group  46  is received in the lens barrel  42 . The combined lens barrel  42  and lens group  46  are received in the top hollow cylinder  441 . The image sensor chip  10  is received in the bottom hollow cylinder  442 . The bottom hollow cylinder  442  comprises a bottom surface  445  contacting with the substrate  20 , and an outer sidewall  446 . The bottom surface  445  defines a sloped surface  4421  extending from the bottom surface  445  to the outer sidewall  446 . The bottom surface  445  and the sloped surface  4421  define an angle therebetween. The angle, in this embodiment, is greater than 30 degrees. A gap  4422  is defined between the substrate  20  and the sloped surface  4421  of the bottom hollow cylinder  442  of the lens holder  44 . 
     The gap  4422  is filled with the adhesive layer  30 . The lens module  40  is disposed on the supporting surface  22  of the substrate  20  via the adhesive layer  30 . 
     The lens barrel  42  comprises a lower surface  422  facing the image sensor chip  10 . The transparent cover  50 , such as an infrared filter, is provided between the image sensor chip  10  and the lens group  46  and is configured for protecting the photosensitive area  12  from contamination and filtering light from the lens group  46 . The transparent cover  50  is secured to the lower surface  422  of the lens barrel  42  by the adhesive layer  30 . Alternatively, the transparent cover  50  may be directly fixed to the lens module  40 . Alternatively, the transparent cover  50  can be fixed to the inner surface of the connecting plate  443 . The transparent cover  50  may be an optical glass plate. 
     In assembly, the adhesive  30  is disposed on the supporting surface  22  of the substrate  20 , when the lens module  40  is assembled on the substrate  20 , the adhesive layer  30  flows into the gap  4422  of the lens holder  44  and contacts with the sloped surface  4421 , which prevents the adhesive layer  30  from overflowing on to the substrate  30 . In addition, the contact area between the adhesive layer  30  and the bottom surface  445  of the lens holder  44  may have complimentary patterns formed therein to increase contact area, thereby, bonding strength between the lens module  40  and the substrate  20  is stronger. 
     Referring to  FIG. 2 , a camera module  200  in accordance with a second exemplary embodiment is disclosed, differing from the camera module  100  only in the lens holder  64 . In this embodiment, the bottom hollow cylinder  642  comprises an inner sidewall  647  facing away the outer sidewall  646 . The bottom surface  645  defines an sloped surface  6441  extending from the bottom surface  645  to the inner sidewall  647 . The bottom surface  645  and the sloped surface  6441  defines an angle therebetween, which in this embodiment, is greater than 30 degree. A gap  6442  is defined between the substrate  70  and the sloped surface  6441  of the bottom hollow cylinder  642  of the lens holder  64 . In this embodiment, the gap  6442  is triangular in shape. 
     Referring to  FIG. 3 , a camera module  300  in accordance with a third exemplary embodiment is disclosed. In this embodiment, the profile of the bottom surface  945  of the lens holder  94  is “V” shaped but is not limited in that configuration. The bottom surface  945  is square shaped, and defines an inner sloped surface  951  extending from the bottom surface  945  to the inner sidewall  941 , and an outer sloped surfaces  952  extending from the bottom surface  945  to the outer sidewall  942 . A first gap  97  is defined between the substrate  96  and the inner sloped surface  951 . A second gap  98  is defined between the substrate  96  and the outer sloped surface  952 . It should note that, the bottom surface  945  of the lens holder  94  can also define a trapeziform gap for accommodating the adhesive layer  95 . Because the profile of the bottom surface  945  is “V” shaped, when the adhesive layer  95  disposes between the bottom surface  945  and the substrate  96 , which not only prevents the adhesive layer  95  from overflowing on to the substrate  96 , but also increases the amount of surface contact between the substrate  96  and the bottom surface  945  via the adhesive  95 . 
     It will be understood that the above particular embodiments and methods are shown and described by way of illustration only. The principles and the features of the disclosure may be employed in various and numerous embodiment thereof without departing from the scope of the invention as claimed. The above-described embodiments illustrate the scope of the invention but do not restrict the scope of the invention.