Abstract:
A CMOS type of image sensor module for use in a mobile camera or a PC camera includes an image sensoring semiconductor chip encapsulated in a transparent block of polymeric material on a substrate having a circuit to which the ship is connected. The image sensoring semiconductor chip is disposed on an upper surface of the substrate as spaced vertically from a digital signal processing second semiconductor chip mounted on a lower surface of the substrate. The transparent polymeric encapsulation material constitutes a sealing resin unit. The digital signal processing second semiconductor chip may also be encapsulated by the sealing resin unit. The sealing transfer unit can be formed by injection and/or transfer molding. The forming of the sealing resin unit by a single molding process keeps production costs low.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This is a Divisional of, and a claim of priority is made to, U.S. non-provisional application Ser. No. 10/854,643, filed May 27, 2004, now U.S. Pat. No. 7,105,904, the contents of which are incorporated herein by reference in their entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to an image pick up device for use in a mobile camera or the like. More particularly, the present invention relates to a CMOS type image sensor module including a semiconductor chip having a CMOS-based sensor for picking up an image, and a built-in digital signal processing semiconductor chip. 
   2. Description of the Related Art 
   An image sensor module of a camera is a multi-chip device that includes an image sensing semiconductor chip and a digital signal processing semiconductor chip. The image sensing semiconductor chip collects optical images, and the digital signal processing semiconductor chip converts the optical images into electrical signals. Based on the particular type of semiconductor used, the image sensor modules are classified as a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS) device. 
   A CMOS type of image sensor module is disclosed in U.S. Pat. Application No. 2003-0025825, entitled “Small Image Pickup Module” filed on Aug. 29, 2002 by Olympus Optical Co., Ltd. 
     FIG. 1  is a cross-sectional view of the disclosed CMOS type of image sensor module. Referring to this figure, the CMOS type image sensor module has an image sensing semiconductor chip  12  and a digital signal processing semiconductor chip  18  which are mounted horizontally on a substrate  11  as spaced laterally from one another. In addition, a discrete lens kit  13  is connected to the substrate  11  by potting material  271  and  272  that also serves to create a seal between the lens kit  13  and substrate  11 . The image sensing semiconductor chip  12  is protected by a transparent cover  25 . The cover  25  and image sensing semiconductor chip  12  are secured to one another and to the substrate  11  by potting material  261  and  262 . The digital signal processing semiconductor  18  is sealed by a syringe-type of potting material. Reference numbers  14 ,  15 , and  16  designate an infrared filter, an optical lens, and a diaphragm, respectively. 
   However, the above-described CMOS type of image sensor module has disadvantages. 
   First, the manufacturing of the CMOS type of image sensor module is a complicated process entailing a high production cost because it involves creating a seal between the lens kit  13  and the substrate  11 . Moreover, the image sensing semiconductor chip  12  and the digital signal processing semiconductor chip  18  are molded to the substrate  11  through separate processes. 
   Second, the difficulties and complexity of the manufacturing process, especially when adapted for mass production of the CMOS type of image sensor module, lead to frequent manufacturing defects. That is, the prior art CMOS type of image sensor module is manufactured with a relatively low productivity. 
   Third, the prior art CMOS type of image sensor module is relatively large because the image sensing semiconductor chip and the digital signal processing semiconductor chip are mounted to the substrate horizontally as spaced laterally from each other. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a CMOS type of image sensor module that can be produced using a relatively simple process. 
   Another object of the present invention is to provide a compact CMOS type of image sensor module. 
   Still another object of the present invention is to provide a CMOS type of image sensor module that is easy to mass produce. 
   According to one aspect of the present invention, a CMOS type of image sensor module includes a substrate having a circuit pattern to which a chip may be wire bonded at either side thereof, a first semiconductor chip for image sensing mounted on an upper side of the substrate and wire-bonded to the circuit pattern, a second semiconductor chip for digital signal processing mounted on a lower side of the substrate and wire-bonded to the circuit pattern, and a sealing resin unit made of transparent polymeric encapsulation material encapsulating at least the first semiconductor chip. 
   In the case in which the sealing resin unit encapsulates only the first semiconductor chip, the second semiconductor chip is sealed using an epoxy molding compound (EMC). 
   In addition, the sealing resin unit may include a screw thread by which a lens kit may be coupled to the unit. The lens kit preferably includes a housing, and an optical lens and an infrared filter disposed vertically relative to one another within the housing. Alternatively, the sealing resin unit itself forms an optical lens. In this case, the lens constituted by the sealing resin unit can be coated with an infrared filter material. 
   According to another aspect of the present invention, a method of manufacturing a CMOS type of image sensor module includes: (a) providing a substrate having an integral circuit pattern to which a chip may be wire bonded at either side of the substrate, (b) mounting a digital signal processing semiconductor chip and a passive device on a lower side of the substrate, (c) wire-bonding the second semiconductor to the circuit at the lower side of the substrate, (d) mounting an image sensing semiconductor chip on an upper side of the substrate, (e) wire-bonding the image sensing semiconductor chip to the circuit at the upper side of the substrate, and (e) molding a transparent polymeric encapsulation material to the substrate over at least one of the chips on the substrate. 
   Preferably, the molding process comprises injection molding. In particular, the molding process may consist of injection molding. In addition, the molding process may comprise transfer molding as performed by conventional transfer molding equipment. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other features and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments thereof made with reference to the attached drawings, in which: 
       FIG. 1  is a cross-sectional view of a prior art CMOS type of image sensor module; 
       FIG. 2  is a cross-sectional view of a first embodiment of a CMOS type of image sensor module according to the present invention; 
       FIG. 3  is a cross-sectional view of a second embodiment of a CMOS type of image sensor module according to the present invention; 
       FIG. 4  is a cross-sectional view of a third embodiment of a CMOS type of image sensor module according to the present invention; and 
       FIG. 5  is a cross-sectional view of a fourth embodiment of a CMOS type of image sensor module according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention now will be described more fully with reference to the accompanying drawings, in which specific embodiments of the invention are shown. Before the description proceeds, however, it is to be noted that the term “molding process” used in the specification refers to any type of molding process, i.e., is not limited to an injection molding process. 
   Referring to  FIG. 2 , a first embodiment of CMOS type of image sensor module  100  according to the present invention includes a substrate  110  having a base member and a circuit pattern  180  at both sides of the base member so that a chip can be wire bonded to the circuit pattern  180  at either side of the base member, a first semiconductor chip (image sensing chip having a CMOS type of image sensor)  120  mounted on an upper portion of the substrate  110  and wire-bonded to the circuit pattern thereof, a second semiconductor chip (digital signal processing chip)  130  mounted on a lower portion of the substrate  110  and wire-bonded to the circuit pattern thereof, and a sealing resin unit  140  of transparent polymeric encapsulation material formed on the surface of the substrate  110  by injection molding and in which the first semiconductor chip  120  is sealed. 
   The CMOS type of image sensor module  100  further includes an epoxy molding compound  160  on the lower portion of the substrate  110  and in which a passive device  162  and the second semiconductor chip  130  are sealed, protective material  144  attached to the side of the sealing resin unit  140 , and a lens kit  170  coupled to the sealing resin unit  140 . To this end, the sealing resin unit  140  has an external thread  142  onto which the lens kit  170  is screwed. 
   The protective material  144  is opaque so as to prevent the transmission of light into the sealing resin unit and is preferably in the form of a tape. The lens kit  170  includes a lens kit housing  150 , and an optical lens  154  and an infrared filter  152  disposed vertically in the lens kit housing  150 . The passive device  162  comprises small electronic components such as a resistor and a capacitor. Gold wires  122  and  132  preferably electrically connect the first semiconductor chip  120  and the second semiconductor chip  130  to the substrate  110 . Reference number  112  designates a flexible printed circuit board (FPCB) that is a mother board to which the CMOS type of image sensor module  110  is mounted. 
   The sealing resin unit  140  may be made of a thermoplastic polymeric material. In this case, the temperature at which sealing resin unit will deform is very low—ranging between 100 and 120° C. Thus, a CMOS type of image sensor module including such thermoplastic polymeric encapsulation material should be connected to the FPCB  112  using a process conducted at a low temperature. Similarly, the CMOS type of image sensor module  100  and FPCB  112  may be joined by applying heat locally at their interface or by using an anisotropic conductive film (ACF). 
   In general, though, the transparent polymeric encapsulation material of the sealing resin unit  140  may be made of polymethylmethacrylate (PMMA), a polycarbonate (PC), a thermosetting transparent epoxy, or a transparent ABS. PMMA is a material widely-used for optical products such as CDs, lenses, and LCD displays. ABS is a thermoplastic resin made from acrylonitrile, butadiene, and styrene, and is widely-used in electronic, automotive, and industrial products. As a transparent epoxy, a non-filler type of transparent epoxy generally used in manufacturing light-emitting diodes (LEDs) can be used. The non-filler type of transparent epoxy can be transfer-molded to the substrate  110  at a temperature of around 150° C. 
   A second embodiment of the present invention will now be described with reference to  FIG. 3 . However, those parts of the second embodiment that are similar to those the first embodiment will not be described for the sake of brevity. 
   Referring now to  FIG. 3 , in the second embodiment of the CMOS type of image sensor module  200 , the sealing resin unit  240  constitutes a plastic optical lens  246  that serves the role of the lens  154  of the lens kit unit  170  of the first embodiment. That is, the plastic lens  246  is formed by the curved upper portion of the sealing resin unit  240 . An infrared filter  252  coats the surface of the optical lens. Reference numerals  222 ,  232  designate bonding wires,  262  a passive device, and  212  a flexible printed circuit board (FPCB). 
   The CMOS type of image sensor modules  100  and  200  can be manufactured as follows. 
   First, a substrate  110 ,  210  including a circuit pattern at both sides thereof is prepared. The doubled-sided substrate  110 ,  210  is similar to that of a ball grid array (BGA) package. Then, a digital signal processing semiconductor chip  130 ,  230  and a passive device  162 ,  262  are mounted on a lower side of the substrate, and the chip  130 ,  230  is wire-bonded to the circuit pattern using gold wires  132 ,  232 . 
   Next, the digital signal processing semiconductor chip  130 ,  230  and passive device  162 ,  262  are sealed within an epoxy molding compound (EMC)  160 ,  260  molded to the lower side of the substrate  110 ,  210  using a conventional process per se. Then, the image sensing semiconductor chip  120 ,  220  is mounted on an upper side of the substrate  110 ,  210  and is wire-bonded to the circuit pattern of the substrate  110 ,  210  using the gold wires  122 ,  222 . 
   Finally, the sealing resin unit  140 ,  240  is formed by molding a transparent polymeric encapsulation material to the upper side of the substrate  110 ,  210 . In the first embodiment, the molding process forms the thread  142  at the upper portion of the sealing resin unit  140 , and by which the lens kit  170  is screwed onto the resin unit  140 . On the other hand, in the second embodiment, the molding process forms a plastic optical lens at the upper portion of the sealing resin unit  240 , and the lens is then coated with an infrared filtering material  252 . A protective material  144 ,  244  in the form of, for example, a tape, can be attached to the side of the sealing resin unit  140 ,  240  to prevent light from being transmitted through the side of the sealing resin unit  140 ,  240 . 
   When the sealing resin unit  140 ,  240  is formed of a PC or a transparent ABS, the injection molding temperature is preferably between 200 and 250° C. and the injection molding pressure is 800 kgf/cm 2 . However, these parameters depend on the specific composition and molecular weight of the transparent polymeric encapsulation material. 
   A third embodiment of a CMOS type of image sensor module according to the present invention will now be described with reference to  FIG. 4 . 
   In this embodiment, a sealing resin unit  340  is formed on both the upper and lower portion of a substrate  310 , i.e., an epoxy compound is not molded to the lower portion of the substrate  310 . The remaining parts are identical to those of the embodiment of  FIG. 2 . For instance, the sealing resin unit  340  has a screw thread  342 , and a lens kit is threaded to the sealing resin unit  342 . The lens kit includes a lens housing  350 , an infrared filter  352 , and an optical lens  354 . Reference numerals  322 ,  332  designate bonding wires,  362  a passive device, and  312  a flexible printed circuit board (FPCB). 
   A fourth embodiment of a CMOS type of image sensor module according to the present invention will now be described with reference to  FIG. 5 . 
   This embodiment is the same as the third embodiment in that a sealing resin unit  440  is formed on both the upper and lower portions of the substrate  410 , i.e., an epoxy compound is not molded to the lower portion of the substrate  410 . In this embodiment, though, like the second embodiment of  FIG. 3 , an optical lens  446  is formed by the upper portion of the sealing resin unit  440 , and the plastic lens  446  is coated with an infrared filter  452 . Reference numerals  422 ,  432  designate bonding wires,  462  a passive device, and  412  a flexible printed circuit board (FPCB). 
   Methods of manufacturing CMOS type of image sensor modules  300  and  400  according to the present invention will be described below. 
   First, a substrate  310 ,  410  including a circuit pattern at both sides thereof is prepared. The doubled-sided substrate  310 ,  410  is similar to that of a ball grid array (BGA) package. Then, a digital signal processing semiconductor chip  330 ,  430  and a passive device  362 ,  462  are mounted on a lower portion of the substrate. The chip  330 ,  430  is wire-bonded to the circuit pattern using gold wires  332 ,  432 . Then, the image sensing semiconductor chip  320 ,  420  is mounted on an upper portion of the substrate  310 ,  410  and is wire-bonded to the circuit pattern of the substrate  310 ,  410  using the gold wires  322 ,  422 . However, this order of mounting the chips to the upper and lower sides of the substrate can be reversed. 
   Next, a transparent polymeric encapsulation material is molded to the upper and lower portions of the substrate  110 ,  210  to form the sealing resin unit  340 ,  440 , and thereby encapsulate the digital signal processing semiconductor chip  330 ,  430  and passive device  362 ,  462 , as well as the image sensing semiconductor chip  320 ,  420 . This molding process can consist of an injection molding process or may comprise a combination of transfer and injection molding processes. 
   In the third embodiment, the molding process can be used to form the thread  342  at the upper portion of the sealing resin unit  340 , and by which the lens kit is screwed onto the resin unit  340 . On the other hand, in the fourth embodiment, the molding process forms a plastic optical lens at the upper portion of the sealing resin unit  340 , and the lens is then coated with an infrared filtering material  352 . A protective material  344 ,  444  in the form of, for example, a tape, can be attached to the side of the sealing resin unit  340 ,  440  to prevent light from being transmitted through the side of the sealing resin unit  340 ,  440 . Finally, the substrate  310 ,  410  is connected under a low temperature to FPCB  312 ,  412  using an ACF. 
   Therefore, advantages of the present invention as described above are as follows. 
   First, the overall manufacturing process is relatively simple. Thus, production costs are kept to a minimum. 
   Secondly, the use of injection molding by the present invention facilitates the mass production of the CMOS type of image sensor modules. 
   Third, the CMOS type of image sensor module is relatively small because the image sensing chip and the digital signal processing chip are arranged vertically one above the other on the substrate. 
   Although the present invention has been particularly shown and described with reference to the preferred embodiments thereof, various changes in the form and details thereof will be apparent to those of ordinary skill in the art that. For example, although the protective material for the sealing resin unit has been described as being in the form of tape, the protective material can take the form of other types of coatings. Accordingly, the present invention can be practiced in ways other than those described in detail in the specification without departing from the true spirit and scope of the present invention as defined by the following claims.