Abstract:
A digital camera module package method includes the steps of: firstly, providing a carrier ( 30 ), which includes a base ( 24 ) and a leadframe ( 320 ). The base has a cavity therein and the leadframe includes a number of conductive pieces ( 322 ); Secondly, mounting an image sensor chip ( 34 ) on the base and received in the cavity, the image sensor having a photosensitive area. Thirdly, providing a plurality of wires ( 36 ), each electrically connecting the image sensor chip and a corresponding one of the conductive pieces of the carrier. Fourthly, applying an adhesive means ( 3262 ) around the image sensor chip that at least partially covers all the wires. Finally, mounting a transparent cover ( 38 ) on the carrier, where an adhesive means fixes the cover in place.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is related to a co-pending U.S. Patent Application Ser. No. 11/453,456, entitled “IMAGE SENSOR CHIP PACKAGE FABRICATION METHOD”, by Steven Webster et al. Such application has the same assignee as the present application and has been concurrently filed herewith. The disclosure of the above identified application is incorporated herein by reference. 
   TECHNICAL FIELD 
   The present invention generally relates to an integrated circuit (IC) chip package fabrication method and, more particularly, to a digital camera module fabrication method with an image sensor chip package. 
   BACKGROUND 
   With the development of wireless communication technologies, increasing numbers of mobile phones and personal digital assistants (PDAs) now include digital cameras as a special feature. Image sensors are a core element of digital cameras. Therefore, image sensors are widely used in digital camera modules in order to convert the optical image data of an object into electrical signals. In order to protect the image sensor from contamination or pollution (i.e. from dust or water vapor), the image sensor is generally sealed in a structural package. 
   A typical image sensor chip package method (not labeled) is disclosed in Chinese Publication Number CN1518079 on Aug. 4, 2004, and is illustrated in  FIG. 10 . The image sensor chip package method includes the following steps: firstly, a plurality of [-shaped conductors  130  are provided. Secondly, plastics are injected to partially enclose the conductors  130 , thereby forming a base  146 . Some of the conductors  130  are exposed outside of the base  146 . Thirdly, a ring-like middle portion  148  is further formed on the base  146  by means of injection. The base  146  and the middle portion  148  cooperatively form a space  150 . Fourthly, an image sensor  152  having a plurality of pads  154  is disposed in the space  150 . Fifthly, a number of bonding wires  156  are provided to connect the pads  154  and the conductors  130 . Finally, a cover  158  is secured to the top of the middle portion  148  via an adhesive glue, thereby hermetically sealing the space  150  and allowing light beams to pass therethrough. 
   In the process of connecting the wires  156 , each wire  156  needs to be connected with the conductor  130 . Furthermore, a larger space is needed in order to conveniently operate. It is obvious that this method of connecting wires  156  is complex and as a result it is also expensive. In addition, the relative large volume of the image sensor chip package results in more dust-particles adhering to the cover  158 , the bottom board and the sidewalls of the base  146 . Thus, more dust-particles will drop onto the chip  152 . The dust-particles obscure the optical path and produce errors in the image sensing process. Accordingly, the quality and/or reliability of the image sensor chip package  100  can be affected. Moreover, the bonding wires  156 , exposed in the space  150 , lack protection and may thus easily be damaged by dust-particles entering the space  150 . 
   Therefore, a new digital camera module fabrication method is desired in order to overcome the above-described shortcomings. 
   SUMMARY OF THE INVENTION 
   One embodiment of a digital camera module package method includes the steps of: 
   providing a carrier including a base and a leadframe, the base having a cavity therein, the leadframe comprising a plurality of conductive pieces, the conductive pieces of the leadframe being embedded in the base and spaced from each other; 
   mounting an image sensor chip in the cavity, the image sensor having a photosensitive area; 
   providing a plurality of wires, each electrically connecting the image sensor chip and a corresponding one of the conductive pieces of the carrier; 
   applying an adhesive means around the image sensor chip and at least partially covering all the wires; 
   mounting a transparent cover to the carrier, the adhesive means adhering to the cover and configured in a manner so as to define a sealing space for a photosensitive area of the image sensor chip therein, and the base and the cover allowing one end of the conductive pieces to be exposed out therefrom; and 
   mounting a lens module on the cover. 
   Other advantages and novel features will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Many aspects of the present digital camera module package 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 image sensor chip package. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views. 
       FIG. 1  is a schematic, cross-sectional view of a digital camera module with an image sensor chip package according to a preferred embodiment; 
       FIG. 2  is a schematic, top-down plan view of the leadframe of  FIG. 1 ; 
       FIG. 3  is a cross-sectional view of the leadframe in  FIG. 2  along a line III-III; 
       FIG. 4  is a schematic, top view of the carrier formed by insert-molding shown in  FIG. 4 ; 
       FIG. 5  is a cross-sectional view after the image sensor is put into the carrier; 
       FIG. 6  is a cross-sectional view showing the adhesive glue surrounding all of the bonding wires; 
       FIG. 7  is a cross-sectional view showing the adhesive glue fixing the cover and defining a small sealing space to seal the photosensitive area; 
       FIG. 8  is a cross-sectional view showing therim of the image sensor package; 
       FIG. 9  is a cross-sectional view showing the barrel and the seat mounted on the image sensor package; 
       FIG. 10  is a schematic, cross-sectional view of a typical image sensor chip package. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Referring to  FIG. 1 , a digital camera module includes a barrel  10 , a seat  20  and an image sensor chip package  30  in accordance with a preferred embodiment. The image sensor chip package  30  includes a carrier  32 , a chip  34 , a number of bonding wires  36  and a cover  38 . 
   The barrel  10  is substantially a hollow cylinder with two open ends so that light can be transmitted therethrough. Several lens elements  12  are disposed in the barrel  10 , and receive incoming light that enters from the outside. The barrel  10  has an outer thread  102  defined in an outer periphery wall thereof. A glass board  14  is disposed in front of the lens elements  12  and covers one end of the barrel  10 . As such, the glass board  14  protects the lens elements  12  from being scraped or otherwise abraded and keeps dust from entering the system. 
   The seat  20  includes a seat body  202  and a flange  204  formed together. The seat body  202  is a hollow cylinder. The flange  204  is formed at a bottom end of the seat body  202 . The flange  204  has a rectangular cavity  2042  defined in a middle thereof opposite to the seat body  202 . The rectangular cavity  2042  communicates with the seat body  202  so that light can be transmitted therethrough. An outer diameter of the seat body  202  is smaller than an edge of the flange  204  so that a step is formed at a connection between them. An inner periphery wall of the seat body  202  defines an inner thread  201  for engaging with the outer thread  102  of the barrel  10 . 
   The carrier  32  of the image sensor chip package  30  includes a number of conductive pieces  322  and a plastic base  324 . The conductive pieces  322  are spaced from each other and aligned in parallel, and cooperatively form the carrier  32  when combined with the plastic base  324 . 
   The image sensor chip  34  is received in the carrier  32 , and is adhered to the bottom of the carrier  32  with an adhesive glue  346 . A top surface of the image sensor chip  34  is arranged with a photosensitive area  344  and a number of chip pads  342  around the photosensitive area  344 . 
   The bonding wires  36  can be made of a conductive material such as, for example, gold or aluminum alloy. One end of each wire  36  is connected/joined with a respective chip pad  342  of the image sensor chip  34 , and the other end of the wire  36  is connected/joined with a respective upper pad  326  forming by the conductive pieces  322 . 
   The cover  38  is transparent and is laid over the image sensor chip  34  which receives light transmitted through the cover  38 . An edge portion of the cover  38  is adhered to the base  324  by a bonding glue  382  and therefore seals the image sensor chip  34  in the cavity of the base  324 . 
   An adhesive glue  3262 , such as a silicone, epoxy, acrylic, or palyarnide adhesive, is applied round the photosensitive area  344  of the image sensor chip  34 . The adhesive glue  3262  surrounds all of the bonding wires  36  and covers the upper pads  326 , and the inner surface of the carrier  32 . The adhesive glue  3262  also adheres to a middle circumferential area of the cover  38  and defines a small sealing space  37  configured to seal the photosensitive area  344  therein. The bonding wires  36  and the adhesive glue  3262  are received in the carrier  32 . It can be seen that the photosensitive area  344  of the image sensor chip  34  is sufficiently protected from outside pollution due to the small volume of the sealing space  37 . The bonding wires  36  are protected by the adhesive glue  3262 , and the conductive pieces  322  are protected by the base  324 . 
   A method of fabricating the digital camera module  100  is disclosed by way of example. In one embodiment, a plurality of image sensor packages  30  are fabricated simultaneously to minimize the cost associated with each individual image sensor package  30 . Referring to  FIGS. 2 and 3 , firstly, a conductor element  302  is provided. The conductor element  320  is formed on a metal plate by etching. The conductor element  321  includes a support beam  321 , many groups of conductive pieces  322  and a number of separate beams  323 . The conductive pieces  322  are punched so that each of the conductive pieces  322  forms a first terminal portion  3220 , a second connecting portion  3222  and a third terminal portion  3224 , where the second connecting portion  3222  interconnects the first and third terminal portions  3220 ,  3224 . The first and third portions  3220 ,  3224  are spaced apart and aligned in parallel to each other. The second portion  3222  is slanted relative to the first and third portions  3220 ,  3224 . Correspondingly, the conductive pieces  322  are divided into two groups. The two groups are symmetrically arranged and the conductive pieces in the same group are parallel to and spaced from each other, thereby forming a plurality of leadframes  320  connected to each other. 
   Secondly, the molten plastic is injected into the conductor element  302  by insert-molding. The plastic is solidified to form the plastic base  324 . The plastic base  324  partially encloses the upper and lower surfaces of each of the leadframes  320 . One end of each of the first portions  3220  is exposed, thus forming a plurality of upper pads  326 . A distal end of each of the third portions  3224  is exposed, thus forming a number of lower pads  328 . The plastic base  324  and each leadframe  130  cooperatively form carriers connected to each other. Each carrier  32  is formed with a trapezoidal cavity. 
   Thirdly, referring to  FIG. 5 , each image sensor chip  34  is received in a corresponding trapezoidal cavity, and is adhered to the bottom of the carrier  32  via an adhesive glue  346 . Alternatively, the adhesive glue  346  can be replaced by any other appropriate adhesive means such as, for example, by metallurgical means. 
   Fourthly, referring to  FIG. 6 , one end of each wire  36  is connected/joined with a respective chip pad  342  of the image sensor chip  34 , and the other end of the wire  36  is connected/joined with a respective upper pad  326  forming by the first portions  3220  of the leadframe  320 . 
   Fifthly, referring to  FIGS. 7 and 8 , each cover  38  is laid over the image sensor chip  34  which receives light transmitted through the cover  38 . An edge portion of the cover  38  is adhered on the base  324  by a bonding glue  382  and therefore seals the image sensor chip  34  in the cavity of the base  324 . The adhesive glue  3262  surrounds all of the bonding wires  36  and covers the first portions  3220 , and the inner surface of the carrier  32 . The adhesive glue  3262  also adheres to a middle circumferential area of the cover  38  and defines a small sealing space  37  configured to seal the photosensitive area  344  therein, The bonding wires  36  and the adhesive glue  3262  are received in the carrier  32 . It can be seen that the photosensitive area  344  of the image sensor chip  34  is protected from outside pollution due to the small volume of the sealing space  37 . The bonding wires  36  are protected by the adhesive glue  3262 , and the leadframe  320  is protected by the base  324 . 
   After that, the conductor element  302  with the plastic base are cut along the rim of each carrier  30  so as to separate a plurality of carriers  30 . At that time, distal ends of each of the conductive pieces  322  are exposed outside. Usually, the conductive pieces  322  are shortened owing to a different shrinkage after the carriers are cut. A kind of fuse technology such as ultrasonic fuse, laser fuse or heat fuse may be used to irradiate the rim of the carrier. Accordingly, the plastic base  324  are melted so as to enclose the conductive pieces  322 . By forming a plurality of image sensor packages  30  simultaneously, several advantages are realized. One advantage is that it is less labor intensive to handle and process a plurality of image sensor packages simultaneously rather than to handle and process each image sensor package on an individual base. By reducing labor, the cost associated with each package is minimized. 
   Finally, referring to  FIG. 9 , several lens elements  12  are received in the barrel  10 . The outer thread  102  of the barrel  10  engages with the inner thread  201  of the seat  20 , whereby the barrel  10  and the seat  20  are connected with each other. The seat  20  is then mounted on the image sensor chip package  30  by welding/glue, with the image sensor  34  aligning with the lens elements  12 . At the same time, the cover  38  is received in the rectangular cavity  2042 . The assembly process of the digital camera module  100  is thus completed. 
   In an alternative embodiment, the arrangement of the conductive pieces of the leadframe  320  can be changed so long as the conductive pieces  322  are spaced from each other. The second portion  3222  can be perpendicular to the first and third portions  3220 ,  3224  rather than being slanted. The base  324  can be of another shape such as cylinder-shaped, or column-shaped with a pentagonal or hexagonal cross-section. Understandably, the image sensor package may also be produced in single units. 
   In the above embodiments, the adhesive glue  3262  may only be disposed around the photosensitive area  344  so as to define a sealing space for protecting the photosensitive area  344 . One main advantage of the digital cameral module with this image sensor chip package is its reliability and high image quality. 
   It is believed that the present embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the invention or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the invention.