Liquid crystal cells – elements and systems – Particular structure – Having significant detail of cell structure only
Reexamination Certificate
1999-11-04
2002-09-24
Parker, Kenneth (Department: 2871)
Liquid crystal cells, elements and systems
Particular structure
Having significant detail of cell structure only
C349S151000, C349S152000, C349S149000
Reexamination Certificate
active
06456353
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates to a display driver integrated circuit module. More particularly, the present invention relates to a flat liquid crystal display driver integrated circuit module.
2. Description of Related Art
Liquid crystal is a material in between a solid and a liquid. When affected by external electric fields, magnetic fields, or heat, molecular orientation of liquid crystal is changed. The photoelectric property of liquid crystal is also varied. The variation of photoelectric property due to externally applied fields can be adjusted, and hence, produces a visual effect that is adapted for the formation of a liquid crystal display (LCD).
A LCD has a low operating voltage, emits no radiation, is lightweight, has a small volume, and has a low power consumption, in addition to other properties. Therefore, LCDs are widely used in products such as portable TVs, mobile phones, camcorders, notebooks, desktop monitors, projection TVs, and other electronic commodities and computer products. It is expected that cathode ray tube (CRT) containing devices will be gradually replaced by LCD devices, and LCD devices will become the mainstream monitor product in the future.
The manufacturing process of a LCD has been being developed in following the trench of a higher contrast ratio, a wider viewing angle, a faster response speed, a higher resolution, a full color display, etc., which yet depend on, for example, the molecular structure of liquid crystal, the color filter, the thin film transistor (TFT), the polarizer, the encapsulant, the integrated circuit mounting technology, the packaging type, etc.
In order to fulfill the requirements of high resolution and miniaturization of electronic commodities, the packaging technique has been changed from the chip on board (COB) process to the tape automated bonding (TAB) process, and further changed into the chip on glass (COG) process, also called the flip chip on glass (FCOG) process, for a very fine pitch requirement.
The COB process is the most widely used process in the early LCDs manufacturing. A chip is mounted on a printed circuit board (PCB) by means of the wire bonding process and the surface mounted technology (SMT). Connections between the PCB with a chip and a liquid crystal panel are accomplished through a flexible printed circuit board (FPCB). Such processes involve the design of the PCB, the treatment of metal layers on connection points, and the requirement of the FPCB for connections.
FIG. 1
illustrates a flow chart for the assembly process of a liquid crystal module (LCM) by means of the prior art tape automated bonding process.
FIGS. 2 and 3
illustrate a top view and a schematic, cross-sectional view, respectively, of a liquid crystal module fabricated by means of the prior art tape automated bonding process.
Reference is made to FIG.
1
. According to a step
100
shown in
FIG. 1
, bumps are fabricated on a driver integrated circuit (IC) first. An inner lead bonding (ILB) process is performed which mounts the driver IC to inner leads of a tape. After encapsulation and testing, an outer lead bonding (OLB) process is performed in which outer leads of the tape is electrically connected to terminals located on an edge of a liquid crystal panel by means of an anisotropic conductive film (ACF).
Then, a step
102
shown in
FIG. 1
follows. By employing an ACF or solder, the tape with driver IC is connected to a PCB. A LCD is controlled under an active matrix driving manner by different functions ICs on the PCB and the driver IC on the tape to produce desired patterns.
A step
104
shown in
FIG. 1
is performed. A backlight, a bezel, a frame, etc., the liquid crystal panel, the tape with driver IC, and the PCB together forms a liquid crystal module.
Reference is made to
FIGS. 2 and 3
, in which a top view and a schematic, cross-sectional view of a liquid crystal module fabricated by means of the prior art tape automated bonding process are illustrated, respectively. Driver ICs
204
are mounted on tapes
202
. The tapes
202
are then respectively connected to a liquid crystal panel
200
and PCBs
206
. Other ICs
208
are mounted to the PCBs
206
as well. A backlight
210
is located under the liquid crystal panel
200
in order to provide a light source.
The COG process, also named as the flip chip on glass process (FCOG), is a flip chip bonding process, which electrically connects driver chips to a liquid crystal panel by means of eutectic metals, polymer resins, or conductive adhesives as connecting media. Bumps of the chips and terminals of a panel are electrically connected for isotropic and anisotropic conduction.
Currently TFT-LCD structure mainly employs the TAB and the FCOG processes for its fabrication. Typical small and medium size (up to about 7 inches) TFT-LCDs employ the FCOG process. For large size TFT-LCDs (over about 12 inches), the TAB process is still be employed in common.
Both the COB process and the TAB process involve the use of PCBs for providing electrical connection paths between a liquid crystal panel and external circuits. However, a pitch width below 180 microns is very difficult to achieve in the PCB manufacture. The COB process can only provide low I/O lead-counts. Even the TAB process still employs PCBs. For the COG process, it involves the solder bump formation, the flip-chip bonding process, and the encapsulation process, and hence, its application in mass production of large size LCD (over about 12 inches) assembly is still not possible.
SUMMARY OF THE INVENTION
Based on the foregoing, the present invention provides a display driver integrated circuit module, which is applicable to a liquid crystal module assembly. Driver ICs are mounted to a flexible base film and electrically connected to it to form the display driver IC module. An application of the display driver IC module in the liquid crystal module assembly can reduce the amount of using PCBs, simplify the manufacturing process, reduce the production cost, the overall size and thickness, the weight, and it is suitable for large size LCD manufacture.
Accordingly, the present invention provides a display driver IC module which is applicable to a liquid crystal module assembly. The display driver IC module comprises a flexible base film and a plurality of driver ICs. The flexible base film includes an interconnecting wiring. Each driver ICs is mounted to the flexible base film, and having a plurality of input/output (I/O) pads electrically connected to the interconnecting wiring. Each driver IC is electrically connected to the corresponding input/output pads of the other driver ICs through the interconnecting wiring on the flexible base film.
Moreover, the present invention provides a structure and method of manufacturing a liquid crystal module. The liquid crystal module includes a display driver IC module, a liquid crystal panel, a backlight, etc. Driver ICs are first connected to a flexible base film to form the display drive IC module. The flexible base film includes an interconnecting wiring fabricated on it. Each driver IC includes a plurality of I/O pads electrically connected to the interconnecting wiring on the flexible base film. Each driver IC is electrically connected to the corresponding I/O pads of the other driver ICs through the interconnecting wiring on the flexible base film. Furthermore, a connecting material is employed for electrical connection between the display driver IC module and the liquid crystal panel. The backlight is located under the liquid crystal panel to form the liquid crystal module.
REFERENCES:
patent: 5029984 (1991-07-01), Adachi et al.
patent: 5293262 (1994-03-01), Adachi et al.
patent: 6191838 (2001-02-01), Muramatsu
patent: 6284086 (2001-09-01), Cardellino et al.
Chi Mei Opto Electronics Corp.
Chung David
J. C. Pattent
Parker Kenneth
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