Tape carrier package and display device using the same

Abstract

A tape carrier package is provided, which includes: a line provided on one surface of a tape substrate; and a semiconductor chip mounted on an other surface of the tape substrate, the semiconductor chip having an electrode which is electrically connected to the line. The line extends from one end to an opposite end of the tape substrate and includes a connection where an intermediate line portion provided in a middle between the ends is electrically connected to the electrode.

Description

[0001] 1. Field of the Invention[0002] The present invention relates to a liquid crystal display device, or the like, used for a computer, word processor, etc., and also to a tape carrier package mounted on the display device which package includes a semiconductor chip for driving a display medium such as for example a liquid crystal material.[0003] 2. Description of the Related Art[0004] FIG. 23 illustrates an example of a liquid crystal display device, which includes: a liquid crystal panel including an upper glass plate 15 and a lower glass plate 16 provided so as to interpose a liquid crystal material (not shown); a backlight unit 21 as a light source; a semiconductor chip 5 for driving the liquid crystal material; a tape carrier package (TCP) 7 connecting the semiconductor chip 5 to the wiring (or lines) provided on the lower glass plate 16; a printed board 23 for connecting a plurality of TCPs 7 together; and a vessel 22 for covering the liquid crystal panel.[0005] Known metho...

AI Technical Summary

Benefits of technology

[0104] In the liquid crystal display device of the present example, the TCPs 7, as being cut from the tape, are connected and secured individually to a wiring pattern 17 formed on the lower glass plate 16 of the liquid crystal panel via the anisotropic conductive film 20. In the figure, the TCP 7 exists entirely over the lower glass plate 16 including the tape. However, a portion of the tape of the TCP 7 or a portion of the semiconductor chip 5 may extend beyond the lower glass plate 16. Even in such a case, there still exists the advantage of the present invention, i.e., not requiring a printed board as a common wiring board.

[0105] The mounting process is performed as follows. The TCP 7 is first supplied as a tape, and is produced by cutting the tape using a metal mold, or the like. Next, the TCP 7 is aligned and temporally connected to a predetermined wiring connection provided on the lower glass plate of the liquid crystal panel. Then, a production press fit process is performed so as to fix the input / output terminal section of the TCP 7 onto the lower glass plate.

[0106] The connection between the lower glass plate 16 of the liquid crystal panel and the TCP 7 is achieved by using the anisotropic conductive film 20. It is possible to simultaneously achieve the connection of the output terminal and the connection of input terminal at once by adjusting the shape of a bonding tool or the apparatus. Even if one of the TCPs 7 turns out to be defective at a test conducted after mounting all the TCPs 7, the defective TCP 7 can be removed from the lower glass plate 16 so as to be replaced with a non-defective TCP 7 without damaging the TCPs 7 adjoining the defective TCP 7. For repair, the defective TCP 7 is removed from the lower glass plate 16 by using some heat, and the lower glass plate 16 is then washed with a special-purpose solvent, after which another non-defective TCP 7 is mounted according to the procedure as described above.

[0107] FIG. 10 illustrates signal flows in an electric connection between the liquid crystal panel and the TCP. As shown in the figure, electric signals are supplied to a plurality of TCPs 7 partially via the wiring pattern 17 provided on the lower glass plate 16 of the liquid crystal panel. In FIG. 10, reference numeral 26 denotes a TCP upper line; and 13 denotes the line in the chip.

[0108] Next, a comparison is made, based on calculations, between the input wiring resistance observed in the present example and that in the conventional ACF-COG method shown in FIG. 25, where all the input lines are provided by the lines on the glass plate. An 11.3-inch SVGA simple matrix type liquid crystal panel is assumedly used in the present example for the test calculation. In this case, 10 liquid crystal driving TCPs having 240 outputs are mounted on each side of the liquid crystal panel, whereby the number of input signal lines for each TCP is about 20.

[0109] Assuming the length of the TCP-mounting section of the 11.3-inch liquid crystal panel is about 220 .mu.m, the length of a single TCP over which components may be mounted is about 22 mm. Assuming the length of one TCP is about 21.5 mm, the average length of the wiring pattern 17 on the lower glass plate 16 is about 0.5 mm.

Problems solved by technology

This increases material cost and the number of steps to be performed, thereby presenting a bottleneck in reducing the cost of a liquid crystal module.

Such a removal may give some mechanical damage to the adjacent TCPs 7, and may also present a burden on the process in terms of the number of steps to be performed, requiring disconnection at three positions (at the right and left input terminals and at an output terminal of the defective TCP 7).

Moreover, the increased area of the TCP 7 will result in an increased material cost.

Thus, the proposed method has some difficulty in repair, does not reduce the number of connection steps; and increases the TCP size.

However, in practice, the configuration as described above is only possible for a relatively small liquid crystal panel of up to about 3 to 6 inches, but is not possible for a currently-dominant large liquid crystal panel of about 10 inches or more.

However, when the glass plate is large, the wiring length on the glass plate is long, a voltage across the length on the glass plate drops, and a valid signal is not transmitted to the liquid crystal driving semiconductor chip.

Such an increase in the size of the glass plate may reduce the number of panels which can be produced from one mother glass, whereby the cost reduction may not be achieved in terms of the module as a whole.

This method requires the flexible wiring board which corresponds to the printed board in the method using a TCP, whereby there is no advantage in terms of the cost and process.

Consequently, wire breaks may occur in the TCP, thus lowering reliability.

However, this method also has a problem that the glass plate wiring substrate is costly, while the wiring resistance thereof is also higher than that of the printed board.

Furthermore, in the case of the COG method, since chips are provided as bare chips, a test is normally made when it is still in the form of a wafer, but no test will be made after it is diced into individual chips.

Therefore, when the semiconductor chip is mounted on the glass plate, it is difficult to ensure the quality of the semiconductor chip (i.e., it is not a Known Good Die).

Particularly, in the case of a large panel on which a large number of semiconductor chips are mounted, the repair rate is likely to increase, thereby possibly increasing the cost.

However, the employment of aluminum requires extension of the width of an internal line of the semiconductor chip.

The increase in chip area results in material costs for the chip to increase.

Additionally, by using the above method, a clock signal can not be transmitted, because the semiconductor generates noise which may influence the signal transmitted therethrough.

For example, a clock signal being transmitted via the semiconductor chip may become corrupted by noise from the chip.

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