Active solid-state devices (e.g. – transistors – solid-state diode – Combined with electrical contact or lead – Wire contact – lead – or bond
Reexamination Certificate
1998-08-31
2001-08-07
Chaudhuri, Olik (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Combined with electrical contact or lead
Wire contact, lead, or bond
C257S059000
Reexamination Certificate
active
06271600
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a redundant wiring apparatus and a method of making the same. The invention also relates to a redundant wiring apparatus and a method of making a redundant wiring apparatus used for a thin film transistor array substrate of a flat panel display device, e.g., a liquid crystal display device.
Recent development of such a liquid crystal display device has focused on the features of small size, light weight and low power consumption. The liquid crystal display device includes a thin film transistor array substrate, a counter substrate and a liquid crystal layer held between the array and counter substrates. The array substrate is provided with an insulation substrate on which a plurality of signal lines and scanning lines are formed in matrix. Pixel electrodes are disposed in the region defined by the signal and scanning lines. The thin film transistors are formed as switching elements in the vicinities of the crossing points of the signal and scanning lines, respectively, and are connected with them through the pixel electrodes. The counter substrate, on the other hand, includes an insulation substrate to which counter electrodes made of transparent conductive films are attached.
The signal and scanning lines are extended out of a display region and are connected with electric power supplying electrodes formed at the surrounding edges of the array substrate. The electric power supplying electrodes are further connected to driver circuits provided outside the array substrate.
In the liquid crystal display device of this sort, it has been recently required that a peripheral frame portion of the display region is made as narrow as possible (the “narrow frame”) to ensure the wide display region. Further, it is necessary to reduce the manufacturing cost and also to improve the production yield.
Where the liquid crystal display device, however, includes the narrow frame, spaces allocated to wires drawn from the display region are so limited that the wiring width and gap become narrow. As a result, open- and/or short-circuited wiring troubles are apt to easily take place in manufacturing.
To improve the reliability by preventing from such open-circuited wiring, a liquid crystal display device which has been available in the market includes signal lines drawn from the display region provided with a redundant, two-layer (parallel) wiring structure. The signal line consists of first and second laminated wires between which an insulation layer is held. Connectors passing through perforations in the isolation layer are provided to connect the first and second wires at both ends located in the display and near the connecting pads, respectively. Thus, with the structure, the signal lines are kept conductive even in the event that either one of the first and second wires is open-circuited. It improves the reliability on the signal lines.
Although the structure prevents the wires from being open-circuited, the short-circuited wiring trouble occur twice as many as that with single wire structure due to redundant wires. In the case of a liquid crystal display device with the narrow frame, the spaces allocated to the lead wires drawn from the display region are so narrow that short-circuited wiring troubles take place more readily.
It is quite difficult not only to detect apoint where such a short-circuited wiring trouble takes place but also to cut it. It is one of the critical factors to automate manufacturing processes of a liquid crystal display device.
SUMMARY OF THE INVENTION
One object of the present invention is to provide a high quality, high production yield, and low cost redundant wiring apparatus which is particularly suitable for the production of a thin film transistor (TFT) array substrate and a method of making a redundant wiring apparatus. The redundant wiring apparatus of this invention and the method thereof are particularly applicable to TFT array substrates for active matrix type liquid crystal display devices.
In order to achieve the object, a redundant wiring apparatus of the invention includes an insulation substrate, an insulation layer, a plurality of first wires formed between the insulation substrate and the insulation layer, a plurality of second wires formed on the insulation layer, the first and second wires each having repair portions in the vicinity of both ends of either one of the first and second wires, and connectors to electrically connect the first wires with the second wires at such both ends as set forth above.
The first wires are in parallel with the second wires with respect to the insulation layers. The first and second wires define a plurality of parallel wiring groups. The wiring redundancy is effective in repairing of the open-circuited wiring at the parallel wiring groups.
The repair portions of the first wires may include sections with which those of the second wires are not overlapped. With the structure, laser repairs are easily carried out.
Where two neighboring first wires are short-circuited, the repair portions are cut off at both ends of either one of such neighboring first wires. Likewise, in the case that two neighboring second wires are short-circuited, the repair portions are cut off at both ends of either one of such two neighboring second wires.
The redundant wiring apparatus of the invention may be applied to display devices which include a display region on the isolation substrate, switching circuits provided in the display region, pixel electrodes, output terminals and a sealing region surrounding the display region.
A plurality of wiring groups are provided to connect the switching circuits with the pixel electrodes and the output terminals and the redundant wires of the wiring group are provided between one end thereof in the sealing region and the other end near the output terminals.
The layout of the redundant wires is complicated and heavy in density. Thus, the wires require the redundant structure to avoid or repair open- and/or short-circuited wiring troubles. The redundant wires are basically comprised of first wires formed between the insulation substrate and the insulation layer and second wires formed on the insulation layer. The first and second wires further include repair portions, respectively, in the vicinity of both ends of either one of the first and second wires. The repair portions of the first wires preferably have sections with which those of the second wire are not overlapped.
In this redundant wiring apparatus, if first wires of neighboring wiring groups are short-circuited, the repair portions at both ends of the first wires are cut off. Similarly, where the second wires of neighboring wiring groups are short-circuited, the repair portions at both ends of either the second wires are cut off.
A method of making a redundant wiring apparatus of the present invention includes the steps of preparing an insulation substrate, forming an insulation layer, forming a plurality of wiring groups, each of which includes first wires formed between the insulation substrate and the insulation layer and second wires formed on the insulation layer, the first and second wires having repair portions in the vicinity of both ends of either one of the first and second wires, and forming connectors in order to electrically connect the first wires with the second wires at such both ends as set forth above. In such a redundant wiring apparatus as made by this method, an open- or short-circuited wiring trouble happens in the neighboring wiring groups, it is easily repaired by laser-cutting of the repair portions as mentioned above in connection with the redundant wiring apparatus.
The above-stated and other objects and technical features of the present invention will become apparent from the following description when taken with the accompanying drawings. It will be understood, however, that the drawings are for the purposes of illustration and are not to be construed as defining the scope of the invention, reference being had for the latter purpose to the claims appended hereto.
Cao Phat X.
Chaudhuri Olik
Kabushiki Kaisha Toshiba
Pillsbury & Winthrop LLP
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