Abstract:
A photosensitive chip element is mounted in a totally clear package. The incoming fight can pass through the package at any angle. The incoming light passed through the package is sensed by the photosensor and converted to a signal indicative thereof. Since the package is clear, no special way of mounting the chip is necessary.

Description:
The present application claims priority under 35 U.S.C. § 119 from Provisional Application No. 60/111,597, filed Nov. 18, 1998. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to CMOS imager devices and plastic packaging thereof. 
     BACKGROUND 
     Image sensors typically are formed using some kind of clear portion to allow light photons to enter the package. Other packaging techniques use plastic injection molds, blown plastics, or plastic transfer molds. 
     These techniques use a flow of plastic packing compound into a cavity. The cavity includes an imager die to be packaged, on a lead frame. Once cooled, the package part is removed from the mold, and the leads are trimmed or formed to form the final packaged part. 
     Typical materials used in the package molding have been opaque. These materials block incoming light. Hence, when these materials are used to package an optical component, they must be used in a way that does not interpose packaging material between the light and the component. 
     These prior art systems have been used with a preformed plastic cavity leadless chip carrier. Using these forms, however, results in higher package cost. 
     SUMMARY 
     The invention relates to packaging a photosensitive device in a clear package. More specifically, the photosensitive device can be a CMOS image sensor that is packaged in clear QFP (Quad Flat Package) or acrylic. The clear material allows the CMOS image sensor to be packaged in the same way as any other CMOS device. Since the material used to package the device is clear, the image sensor can be directly packaged in the package. This new packaging means results in lower cost devices that are more readily integrated with acrylic optics. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other aspects will now be described in detail with respect to the accompanying drawings, wherein: 
     FIG. 1 shows a chip packaging system; 
     FIG. 2 shows an imager device in a packaging system as shown in FIG. 1 receiving incoming light; and 
     FIG. 3 shows a double sided image sensor in a packaging system in accordance with the invention. 
    
    
     DETAILED DESCRIPTION 
     The standard cavity mold approach used in CMOS is used according to the present application. The package is formed of clear structural plastic, such as QFP or an acrylic. Optionally, the entire package is transparent. The transfer mold approach is used in its standard way as is known in the art, but modified to use the melting and/or flow temperature for the QFP. The pressure and time in the mold are also modified according to the manufacturer&#39;s recommendations. The mold forming cavity may also be modified to allow for features and a different viscosity of the clear mold compound. 
     The final device forms a standard type CMOS die in a totally clear package as shown in FIG.  1 . The CMOS dies, is, for example, a photosensitive device with electrical connections, for example, an active pixel sensor. The perimeter of the device has these electrical connections, which are connected to the electrical connections  108  on the image sensor chip. 
     FIG. 1 shows an exemplary embodiment of the package  14  of the invention and illustrates the different dimensions of the various package  10  features. As shown in FIG. 1, the package center  102  generally coincides with the imager array center  101 . The package  14  has a number of different feature size parameters shown, including dimension “A” defining the overall package  14  width, which can be about 550 mils (0.550 inch). Dimension “B” defines an interior width of a cavity  16  for receiving the imager chip (e.g., die  12 ), which can be about 410 mils. Dimensions “C” and “F” define the imager chip widths, which can be about 239 mils and 224 mils, respectively. Dimensions “D” and “E” define the side lengths of the imager photo array  18 , which can be about 112 mils and 92 mils, respectively. Dimension “G” defines the length of an electrical connection  106  measured from the edge of the package perimeter to the initiation of the electrical connection&#39;s  106  bend region; the dimension can be about 30 mils. Dimension “H” defines another length of the electrical connection  106  measured from the bend region to the electrical connection&#39;s  106  terminating end; the dimension can be about 15 mils. Dimension “I” defines a spacing length between adjacent electrical connection members  106  and can be about 39 mils. 
     FIG. 1 shows the package including different sizes of the different package parts. As shown in FIG. 1, the package center  102  is inside the array center  101 . In addition, the package has a number of different size parameter shown including the size a witch&#39;s 550 mills, besides be witch&#39;s 410 mills, the size see which is 239 mills, the size of the witch&#39;s 112 mills, size the witch&#39;s 92 mills, the size F. witch is 224 mills, the size G. witch&#39;s 30 mills, the size age witch&#39;s 15 mills, and the size by a which in 39 mills. 
     As shown in FIG. 2, light photons  200  impinge the photodetector  199 . These photons  200  can be accumulated in the silicon substrate under the photogate PG as  202 ,  204 . The accumulated photons are stored as charge or some other form, which can be later read out. However, if the whole package is clear, as shown in FIG. 2, then photons  200  can be received from any conceivable angle relative to the photodetector  199 , such as the angle shown as  205  in FIG. 2. A window, which would presumably be in the area shown as  210  in FIG. 2, would presumably block that photon. 
     Another application is shown in FIG.  3 . The device is packaged with two image sensor elements  300  and  310 , which respectively receive incoming light from two different sides  315 ,  317 . Another image sensor  312  can receive light from the top  320 . Since the package  299  is clear, the image sensors can be freely located within the package perimeter to receive incoming light from any direction. 
     Other modifications are contemplated. For example, other clear materials may be usable for packaging the chip.