Radiant energy – Photocells; circuits and apparatus – Housings
Reexamination Certificate
1998-12-29
2001-01-09
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Housings
C250S208100, C257S434000
Reexamination Certificate
active
06172361
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to the packaging and assembly of electronic circuitry and in particular to methods for mounting an imager to a support structure and circuitry and systems embodying the same.
2. Description of the Related Art
Charged-coupled device (CCD) imaging is a mature technology which has been used for many years for generating still or video images on any one of a number of display devices. While providing high quality images, CCD imagers have, at least until recently, been expensive. Since the cost of packaging the device was only a small fraction of the overall cost of the CCD imager, no significant efforts were made to trim packaging costs. However, as the cost of CCD imagers has dropped, the packaging costs have correspondingly become a significant factor in the overall cost of the packaged device. This cost factor is particularly relevant to consumer applications, such as digital cameras.
While CCD imagers produce high quality images, for lower cost-lower performance applications, again such as digital cameras, CMOS imagers are frequently used. While producing lower quality images, these imagers are relatively inexpensive, can be integrated onto a single chip along with ancillary circuitry, and allow for some active circuitry to be built within each pixel. In low-performance-low cost applications based on the less expensive CMOS technology, reducing package costs becomes more critical. Additionally, the use of the CMOS technology forces the makers of CCD imaging products to become more focused on reducing package costs.
One specific area where packaging is a significant factor relates to the packaging of the imager and its subsequent marriage to a printed circuit (PC) board or other support/interconnection structure. Presently, some CCD imagers are packaged in a conventional ceramic or plastic packages with a glass lid which allows photons to pass to the CCD element array. For small-format imagers, this type of packaging costs exceeds the cost of the imager chip itself. Moreover, this type of packaging is somewhat bulky and difficult to handle during PC board assembly. CCD imagers have also been packaged in QFP-style packages and in clear mold compound. These options are also not easy implement nor assemble to a PC board.
Thus, the need has arisen for methods of marrying CCD and CMOS imagers and similar photonic sensors to a support/interconnect structure such as a PC board. In addition, these methods should allow for the assembly of circuits and systems which are less expensive and more compact.
SUMMARY OF THE INVENTION
A method is disclosed for mounting a semiconductor device on a supporting structure, the semiconductor device having a surface including a defined area for receiving photons and a plurality of conductors disposed in a pattern adjacent to the defined area for establishing connections to the device. An aperture is formed through the supporting structure and is sized to correspond to a size of the defined area of the semiconductor device. Conductors are formed on the supporting structure adjacent to the aperture in a pattern corresponding to the pattern of the conductors on the semiconductor device. The semiconductor device is mounted to the supporting structure such that the conductors on the semiconductor device contact the conductors on the supporting structure and the defined area of the semiconductor device is exposed to photons through the aperture.
The present inventive concepts have substantial advantages over the prior art. Among other things, photonic sensitive devices, such as CCD or CMOS imagers, easily can be mounted on a structure, such as a PC board, without the traditional ceramic or plastic package. This in turn, reduces costs and allows for more compact and lower profile on the board surface.
REFERENCES:
patent: 5043845 (1991-08-01), McDermott et al.
Harris Brannon
Holberg Douglas
Cirrus Logic Inc.
Le Que T.
Murphy, Esq. James J.
Violette, Esq. J. P.
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