Abstract:
An optical semiconductor package includes a substrate, a chip, a plurality of bonding wires, a window, a supporter, and an encapsulant. The chip is disposed on the substrate and has an optical element. The bonding wires are used for electrically connecting the chip to the substrate. The window is supported on the supporter and positioned over the optical element of the chip. The encapsulant is overmolded on the substrate for fixing the window and encapsulating the chip and the bonding wires.

Description:
RELATED APPLICATIONS  
       [0001]     This application is a divisional of U.S. application Ser. No. 10/667,605, filed Sep. 23, 2003, the disclosure of which is incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an optical semiconductor package, and more particularly, to an optical package which is manufactured by the overmolding process.  
         [0004]     2. Description of the Related Art  
         [0005]     Referring to  FIG. 1 , it depicts a typically optical package  10  in prior art. The optical package  10  comprises a carrier or a substrate  12  and a chip  20  mounded on the substrate  12 . The substrate  12  has a sidewall  16  which surrounds the substrate  12 . A transparent lid  32  is mounted on the sidewall  16  by an adhesive  34  so as to form a hermetic cavity  30  and transmit the light interacting with the chip  20 . The chip  20  has optical elements  22 , such as optical sensors or imaging sensors, and is disposed in the cavity  30 . The chip  20  is electrically connected to a plurality of bonding pads  18  of the substrate  12  by a plurality of bonding wires  26 . The bonding pads  18  on the upper surface of the substrate  12  are electrically connected to the solder pads  14  on the bottom surface thereof through traces or vias  19 . Because of the requirements of the manufacturing process, the substrate  12  is typically made of caramel, i.e., the substrate  12  is a kind of ceramic substrate. Furthermore, the bonding pads  18  and the solder pads  14  are disposed on the upper surface and the bottom surface of the substrate  12 , respectively, so the substrate  12  is a multilayer structure.  
         [0006]     However, the multilayer ceramic substrate  12  has long delivery lead times and is substantially expensive. The bonding wires  26  are connected to the bonding pads  18  and the chip  20  which are recessed in the cavity  30 , so the cavity  30  or the space surrounded by the sidewall  16  has to be large enough that the wire bond tool (not shown) can gain access to the bonding pads  18  and the chip  20 . Therefore, the cost of the substrate  12  is further increased. The ceramic substrate  12  is supplied typically as single units or small arrays and hence is assembled in single units or small arrays, rather than large matrix arrays, so the assembly cost of the package  10  is further increased.  
         [0007]     Accordingly, there exists a need for an optical package which can use a planar substrate and be mass-produced to reduce the manufacturing cost of the optical package.  
       SUMMARY OF THE INVENTION  
       [0008]     It is an object of the present invention to provide an optical package with a planar substrate for mass-producing and reducing the manufacturing cost.  
         [0009]     In order to achieve the above object, the present invention provides an optical semiconductor package comprising a substrate, a chip, a plurality of bonding wires, a window, a supporter, and an encapsulant. The chip is disposed on the substrate and has an optical element. The bonding wires are used for electrically connecting the chip to the substrate. The window is supported on the supporter and positioned over the optical element of the chip. The encapsulant is overmolded on the substrate for fixing the window and encapsulating the chip and the bonding wires.  
         [0010]     Accordingly, the substrate of the optical semiconductor package does not have to be provided with a cavity for receiving the chip, so the substrate can be substantially planar and be an organic laminate or ceramic substrate such that the cost of the substrate is substantially reduced. Furthermore, according to the manufacturing processes of the present invention, the substrate in matrix array can be utilized for mass production and the cost of the optical semiconductor package can be further reduced. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]     Other objects, advantages, and novel features of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawing.  
         [0012]      FIG. 1  is a schematic cross-sectional view of an optical package in the prior art.  
         [0013]      FIG. 2  is a schematic cross-sectional view of an optical package according to an embodiment of the present invention.  
         [0014]      FIG. 3  is a schematic cross-sectional view of an optical package according to another embodiment of the present invention.  
         [0015]      FIG. 4  is a schematic cross-sectional view of an optical package according to a further embodiment of the present invention.  
         [0016]      FIG. 5  is a schematic cross-sectional view of an optical package according to a still further embodiment of the present invention.  
         [0017]      FIG. 6  is a schematic cross-sectional view of an optical package according to yet another embodiment of the present invention. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0018]     Referring to  FIG. 2 , it depicts an optical package  100  according to an embodiment of the present invention. The optical semiconductor package  100  comprises a carrier or substrate  112  which is substantially planar and a chip  120  mounted on the substrate  112 . The substrate  112  can be either an organic laminate or a ceramic substrate. The chip  120  has optical elements  122 , such as optical sensors or imaging sensors, and is electrically connected to a plurality of bonding pads  118  of the substrate  112  by a plurality of bonding wires  126 . The substrate  112  is further provided with solder balls  114  electrically connected to the bonding pads  118  for being electrically connected to an external printing circuit board (not shown).  
         [0019]     A supporter  140  is disposed on the substrate  112  and is provided with a shoulder  144  for supporting and holding a window  142 . Then, an encapsulant  130  is formed by overmolding or insert molding process and the window  142  is kept in place. The window  142  is typically positioned above the optical elements  122  of the chip  120  for receiving or transmitting the light interacting with the optical elements  122 . The encapsulant  130  is transparent plastic, such as acrylate, nylon, polycarbonate, and the like. The supporter  140  can be made of thermal conductive material for serving as a heat sink. Alternatively, the supporter  140  can be made of any plastic, such as PPS, Polycarbonate, LCP and the like, for reducing the cost.  
         [0020]     The dimensions of the window  142  are designed such that the window  142  does not interfere with the bonding wires  126 . The dimensions and shape of the supporter  140  depend on the height of the apexes of the bonding wires  126 , the dimensions of the chip  120 , and dimensions of the substrate  112 . The space or gap between the window  142  and the optical elements  122  of the chip  120  is optimized for overmolding and for light transmission. That is, the gap needs to be large enough to allow the encapsulant  130  to be filled without disturbing the bonding wires  126  or the optical elements  122  and the gap needs to be small enough to permit sufficient transmission of light to ensure adequate operation of the optical sensor.  
         [0021]     The material of the window  142  depends on the optical requirements. For example, the material of the window  142  can be glass for the light at the wavelength above 320 nm, or quartz for ultraviolet (UV) light. The window  142  also can be made of optically transparent plastic, such as acrylate, nylon, polycarbonate, and the like.  
         [0022]     For high volume applications, the supporter  140  and the window  142  can be made integrally and made of plastic, such as acrylate, nylon, polycarbonate, and the like.  
         [0023]     Now referring to  FIG. 3 , it depicts an optical semiconductor package  200  according to another embodiment of the present invention. The optical semiconductor package  200  is similar to the optical semiconductor package  100 , and the identical elements are designated with the similar reference numerals. The optical semiconductor package  200  further comprises two paired snapping elements including a groove  244  and a protrusion  248  which are disposed on the supporter  240  and the window  242 , respectively. The protrusion  248  of the window  242  is snapped with or held in the groove  244  of the supporter  240  so as to securely fix the window  242  on the supporter  240  and keep the window  242  in place during the overmolding process. Further, the paired snapping elements, i.e. the groove  244  and the protrusion  248 , are cooperated with each other to seal the junction of the supporter  240  and the window  242  and further prevent the encapsulant  230  from flushing over the window  242  during the overmolding process. Besides, since the window  242  and the supporter  240  are joined together, the window  242  and the supporter  240  can be handled more easily.  
         [0024]     Now referring to  FIG. 4 , it depicts an optical semiconductor package  300  according to further another embodiment of the present invention. The optical semiconductor package  300  is similar to the optical semiconductor package  100 , and the identical elements are designated with the similar reference numerals. The optical semiconductor package  300  further comprises a lens  342  in place of the window  142  of the optical semiconductor package  100 . The lens  342  is used for focusing the light on to the optical elements  322  of the chip  320  and thus increasing the intensity of the light, thereby increasing the sensitivity of the optical semiconductor package  300 .  
         [0025]     Now referring to  FIG. 5 , it depicts an optical semiconductor package  400  according to still another embodiment of the present invention. The optical semiconductor package  400  is similar to the optical semiconductor package  100 , and the identical elements are designated with the similar reference numerals. The optical semiconductor package  400  further comprises a window  442  directly disposed or mounted on the optical element  422  of the chip  420  by an adhesive  440 .  
         [0026]     The adhesive  440  is a thin layer for retaining the high optical transmission to the chip, and can be made of a material which is of high optical transmission, such as acrylate. It will be apparent to those skilled in the art that the encapsulant  430  of the optical semiconductor package  400  can be made of an opaque material because the encapsulant  430  does not cover the optical elements  422  of the chip  420 . The window  442  is further provided with a plurality of mold locks or ledges  444  for securing the window  442  in the encapsulant  430 .  
         [0027]     Now referring to  FIG. 6 , it depicts an optical semiconductor package  500  according to still another embodiment of the present invention. The optical semiconductor package  500  is similar to the optical semiconductor package  200 , and the identical elements are designated with the similar reference numerals. The optical semiconductor package  500  is provided with a supporter  540  which is hermetically disposed on the substrate  512  to form a cavity  550 . The encapsulant  530  encapsulates the supporter  540  so as to fix the supporter  540  on the substrate  512 . The chip  520  and the bonding wires  526  are positioned in the cavity  550 . The window  542  is hermetically disposed on the supporter  540  for transmitting light into and out of the cavity  550 . As indicated in the foregoing description, the substrate of the optical semiconductor package according to the present invention is not required to have a cavity for receiving the chip, so the substrate can be substantially planar and be an organic laminate or ceramic substrate such that the cost of the substrate is substantially reduced. Furthermore, according to the manufacturing processes of the present invention, the substrate in matrix array can be utilized for mass production and the cost of the optical semiconductor package can be further reduced.  
         [0028]     While the foregoing description and drawings represent the preferred embodiments of the present invention, it will be understood that various additions, modifications and substitutions may be made therein without departing from the spirit and scope of the principles of the present invention as defined in the accompanying claims. One skilled in the art will appreciate that the invention may be used with many modifications of form, structure, arrangement, proportions, materials, elements, and components and otherwise, used in the practice of the invention, which are particularly adapted to specific environments and operative requirements without departing from the principles of the present invention. The presently disclosed embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims and their legal equivalents, and not limited to the foregoing description.