BEST MODE FOR CARRYING OUT THE INVENTION

[0034] The presently preferred embodiment envisions a die on a laminated substrate package having a plastic cover, but the material of the package or specific package type is not critical to the invention. The present invention is compatible with existing manufacturing techniques and may be incorporated into various packaging technologies. For example, the present package may be ceramic or plastic and its structure may be applied to leadless chip carriers packages, ball grid array packages, dual-inline packages, and other IC package types known in the art.

[0035] With reference to FIG. 6 , the present invention is preferably applied to a plastic package modularly so assembled from a cover piece 81 and a substrate base 83 . Plastic is preferred since it reduces manufacturing costs and provides an opaque, dark color for the camera chamber. To mitigate heat problems, an image sensor die within package 80 is preferably accessed through a wire socket 85 next to upper cover 81 . Other methods known in the art of removing heat from an IC package, such as the use of heat sinks, are likewise applicable to the present invention. Substrate carrier base 83 is preferably a laminated substrate structure, which permits the routing of wire leads along its surface. This facilitates the routing of wire socket 85 to wire leads coupling the image sensor die housed within IC chip package 80 . Alternatively, IC chip package 80 may follow more conventional structures providing access to the image sensor die via a ball grid array or lead lines extending out of package 80 rather than using a wire socket. Additionally, package 80 may optionally be given a metal coat, such as electroless nickel plating, to reduce electromagnetic interference, EMI. More critical to the invention, cover 81 holds various imaging components that together with the image sensor die, not shown, constitute a complete imaging module for an electronic camera.

[0036] Package cover 81 in accord with the present invention includes a surface opening exposing a cavity topped by a filter glass 87 that provides a dust cover, a hermetic seal, and IR filtering. Within the cavity, an optical lens 89 attached to a frame structure 91 form a lens-and-frame assembly that is optically coupled to an image sensor die through an optical aperture. Frame structure 91 preferably has a ring shape and together with optical lens 89 form the top of a chamber within the cavity for the image sensor die. Optical lens 89 is maintain at a proper focal distance from the image sensor die by an adhesive having a highly controllable curing activation mechanism. Such types of adhesives may have a curing action selectively activated by the presence of a controllable agent or catalyst such as a chemical agent, heat, or energetic short-wave light such as UV light. The curing stage is activated only in the presence of the specific controllable catalyst. In the presently preferred embodiment, the preferred adhesive is UV cure adhesive and it is used in a manner described below. In the presently preferred embodiment, filter glass 87 , optical lens 89 , and frame 91 are held within a barrel-shaped housing 93 , but this is not critical to the invention. It is to be understood that upper cover 81 may have other shapes more conventional in the art.

[0037] With reference to FIG. 7 , for example, an alternate embodiment of the present invention is an image sensitive, IC chip package 97 having a more conventional shape similar to that of a dual inline package, DIP. All elements similar to those of FIG. 1 are identified with similar reference characters and are described above. In the present case, wire leads 95 are not encased within a wire socket 85 , as shown in FIG. 6 , but rather protrude out from the sides of image sensitive IC chip package 80 . Additionally, the window opening over optical lens 89 is circular in shape, but a rectangular window opening, such as shown in FIG. 6 , is preferred due to compatibility with existing fabrication techniques. In the preferred embodiment, IC chip packages 80 and 97 are constructed from resin molded plastic, but they may alternatively be constructed from ceramic or from other materials known in the art.

[0038] With reference to FIG. 8 , fabrication of the present image sensitive, IC chip package in accord with the present invention begins by attaching an image sensor die 101 to a substrate carrier base 83 using die attach epoxy. Base 83 is preferable of the laminated substrate type, which facilitates the routing of leads on the surface of base 83 . Laminated substrate bases are typically used in multi-chip packages for routing interconnections between multiple dies, but in the present example it is used to facilitate routing between image sensor die 101 and a wire socket 85 , such as that shown in FIG. 6 . However, neither the use of a laminated substrate base nor a wire socket is critical to the invention, as explained above, carrier base 83 may be of any appropriate material used in the construction of a BGA package, DIP package, LCC package, etc. Returning to FIG. 8 , the epoxy is then cured to set image sensor die 101 in place. As it would be understood by those versed in the art, image sensor die 101 may consist of an array of light sensitive charge coupled devices, CCD. As light impacts the array of CCD devices, charge is accumulated at each CCD device in proportion to the intensity of the light. The accumulated charge in the array of CCD devices produces an electronic image of the received light. For illustrative purposes, the area defining the CCD array on image sensor die 101 is represented by a rectangular shape 103 near the top surface.

[0039] With reference to FIG. 9, a wire bonding operation then connects the communication, I/O, bond pads of sensor die 101 to substrate bond fingers 105 a. In the present example, substrate bond fingers 105 a are routed beyond substrate carrier base 83 to form wire leads 105 b in a manner similar to the package type shown in FIG. 7 . The presently preferred package type, however, uses a wire socket 85 , as shown in FIG. 6 . Therefore, FIG. 10 shows an alternate preferred embodiment wherein substrate bond fingers 105 a are routed along the surface of laminated substrate base 83 to form wire leads 105 b protruding upward from the surface of substrate carrier base 83 . Wire leads 105 b are preferably arranged in two rows and mate with a wire socket 85 , as indicated in FIG. 6 .

[0040] With reference to FIG. 11 , an upper cover 81 designed for use with the structure of FIG. 10 has a surface opening exposing the start of a cavity defined by walls 108 . A first shelf 107 along the upper perimeter of the cavity will hold a filter glass, not shown, and a second shelf 109 along the lower perimeter of the cavity will hold an optical lens-and-frame assembly, not shown, below the filter glass. The second shelf, or lens shelf, 109 protrudes inwardly from cavity walls 108 and forms an aperture opening 111 for exposing a chamber in which image sensor die 101 is located. As stated above, wire socket 85 will mate with wire leads 105 b of FIG. 10 . Wire socket 85 is preferably attached to substrate 83 separately from cover 81 to facilitate manufacture of the present package. Upper cover 81 is attached to substrate base 83 using epoxy, and wire socket 85 is mated with wire leads 105 b. Care should be taken to assure that aperture opening 111 is over image sensor die 101 . FIG. 12 shows a sectional view of wire socket 85 , upper cover 81 , and substrate base 83 taken along lines 12 - 12 after upper cover 81 has been attached to substrate base 83 .

[0041] With reference to FIG. 12 , all elements similar to those of FIGS. 6 - 11 are given similar reference characters and are defined above. This cut-out view of upper cover 81 more clearly shows the features of the present chip package housing. First shelf 107 will eventually support a filter glass and lens shelf 109 will support an optical lens-and-frame assembly. As shown, image sensor die 101 lies within a cavity chamber formed by substrate base 83 , the inner walls 110 of upper cover 81 , and the underside of lens shelf 109 . In effect, the underside of lens shelf 109 forms the ceiling having a chamber opening formed from the edge of the lens shelf 109 and constituting an aperture opening 111 over the light receiving area 103 of image sensor die 101 .

[0042] The height of the ledge support provided by lens shelf 109 is preferably selected to provide a gross focal distance from the lens-to-frame assembly to image sensor die 101 . Various lens-and-frame assembly structures are suitable for the present invention. It is desirable, however, that the selected lens-and-frame assembly be easily movable within cavity walls 108 .

[0043] With reference to FIG. 13 , construction of a preferred lens-and-frame includes two interlocking pieces 131 and 141 . The upper piece 131 includes an upper lens 133 attached to a plastic top support frame 132 having pawl extensions 135 . Upper lens 133 is shown to have a convex arch 133 a on top and a similar upward arch 133 b on its bottom. The lower piece 141 includes a lower lens 143 attached to a plastic base support frame 142 having ratchet mechanism 145 for interlocking with pawl extensions 135 of upper piece 131 . Lower lens 143 is shown to have downward arch 143 a on its under side and a similar downward arch 143 b on its top side. Walls 144 form a space separating the upper 133 and lower 143 lenses, which together function as a composite lens for the presently preferred lens-and-frame assembly. Lower piece 141 preferably includes handling knobs 147 for maneuvering it into place within the cavity of an IC package. An optional second optical aperture is provided by a filter 149 may be inserted between upper and lower pieces 131 and 141 . Filter 149 , is not necessary since package cover 81 of FIG. 12 already includes a first optical aperture 111 .

[0044] FIG. 14 shows a cross-sectional view of the preferred lens-and-package assembly after upper and lower pieces 131 and 141 have been interlocked together. Interlocked upper and lower pieces 131 and 141 together define the final frame structure 91 . Similarly, the upper lens 133 and lower lens 143 of FIG. 13 function together to constitute one composite optical lens 89 in FIG. 14 . Of particular interest are optional handling knobs 147 , which facilitate the handling the final frame structure 91 into the cavity defined by walls 108 of FIG. 12 .

[0045] With reference to FIG. 15 , an adhesive having a highly controllable curing mechanism, such as UV cure adhesive 113 is applied to lens shelf 109 . A lens-and-frame assembly consisting of lens 89 and frame 91 is then placed on UV cure adhesive 113 . As shown, the lower portion of lens 89 aligns with aperture opening 111 of lens shelf 109 . At this point, adhesive 113 has not been cured and lens frame 91 may be freely adjusted.

[0046] With reference to FIG. 16 , IC package 80 is then connected to electronic focus testing equipment 115 , symbolically represented as a computer, and image sensor die 101 is activated. Since lens frame 91 is free to move, the focal distance of lens 89 to image sensor die 101 may be adjusted to achieve an optimal focus sharpness with respect to a predetermined focal plane 114 , as determined by test equipment 115 . The movement of lens 89 is illustrated by up-down arrow 117 , but it is to be understood that lens 89 may also be adjusted laterally. Once the optimal focal distance and position has been obtained, a source of UV light, not shown, is applied to UV cure adhesive 113 , which activates its curing stage and thereby holds lens 89 in focus. As shown, lens 89 will likely protrude through aperture 111 into the chamber where die 101 lies.

[0047] With reference to FIG. 17 , an epoxy seal is then used to attach filter glass 87 to filter shelf 107 of upper cover 81 . This assembly consists of two epoxy joints which has proven to form reliable seals. IC chip package 80 therefore incorporates all the sub-components of an electric camera's image module, which in the prior art is held in a separate housing from the IC chip package and constructed into a complicated modular assembly. In other words, the present image sensitive, IC chip package 80 includes an image sensor die 101 , a filter 87 , an optical lens 89 , and an aperture 111 for lens 89 .

[0048] As stated earlier, IC chip package 80 is preferably a plastic molded package. Therefore, IC chip package 80 is preferably coated with a metal film to provide sensor die 101 with shielding from electromagnetic interference, EMI. Thus, the integrated upper cover 81 of the present invention holds an IR filter in place, holds an optical lens at an optical focal distance through an aperture to a sensor die, and provides environmental and EMI protection to the image sensor silicon die. This permits the fabrication of a miniature camera module for portable electronics like cellular phone, pagers, PC cameras, etc.