JPH0640249B2 - Display panel mounting board - Google Patents

Description

The present invention relates to a display panel mounting board in which a display panel such as a liquid crystal (LCD) panel is mounted on a wiring board by adhesion.

(b) Conventional Technology In electronic calculators and various electronic devices, low power consumption and thin LCD panels have been widely used as display bodies. In addition, not only characters but also high-resolution graphic display is often required as display contents. In order to display a graphic pattern, generally, the display surface has a dot matrix structure, and an X-direction transparent electrode and a Y-direction transparent electrode are formed as electrodes. The display panel mounting board is completed by mounting the display panel on which the transparent electrodes in the XY directions are formed on the wiring board via the anisotropic conductive rubber (rubber having conductivity only in one direction). . FIG. 9 shows a conventional display panel mounting substrate using an LCD panel as a display panel. In the figure, 1 is LC
D panel, 2 is a wiring board, and 3 is anisotropic conductive rubber.

(c) Problems to be Solved by the Invention By the way, since the transparent electrode can be formed into a thin film by vapor deposition, sputtering, etc., in the high density display panel, the X direction transparent electrode and the Y direction transparent electrode are mainly used. It is formed by this vapor deposition or sputtering. That is, in this type of display panel, the pitch between the transparent electrodes and the conductor width of the electrodes can be made extremely small.

However, the wiring pattern on the wiring board is not formed by vapor deposition or the like, and usually, a copper clad laminate is used as a starting base material and a desired wiring pattern is formed by etching. Therefore, the thickness of the wiring pattern is considerably thicker than that of the transparent electrode. That the film thickness is large means that the pitch of the wiring pattern and the conductor width cannot be made sufficiently small. The reason for this is that if the film thickness is large, the etching time must be lengthened accordingly, but the so-called side-etch effect cannot be ignored, and the conductor width of the wiring pattern does not break due to the side-etch effect. It is necessary to keep the pitch sufficiently large.

That is, in the conventional display panel mounting board, the pitch of the transparent electrodes and the conductor width of the display panel could be made extremely small, but the pitch of the wiring lines and the conductor width of the wiring board could not be made sufficiently small. In addition, the display resolution does not increase so much.

It is an object of the present invention to devise a wiring board portion for connecting a wiring board and a display panel, thereby substantially increasing the wiring line density at the connection portion and increasing the display resolution. To provide.

(d) Means for Solving the Problems The present invention has a wiring board portion connecting a wiring board and the display panel with a multi-tiered substrate structure, and a wiring line on a wiring board connected to a transparent electrode. Divided into a plurality of blocks, the wiring line of each block is formed in each step of the substrate structure of the plurality of steps, between each step and the transparent electrode,
An anisotropic conductive rubber and an insulating film that selectively opens between transparent electrodes facing each wiring line and a single transparent electrode to which the wiring line should be connected are arranged. To do.

(e) Operation In the display panel mounting board according to the present invention, the wiring line on the wiring board is divided into a plurality of blocks, and the wiring line of each block is formed in each step portion of the substrate structure having a plurality of steps. Between each step and the transparent electrode, an anisotropic conductive rubber is selectively opened between a transparent electrode facing each wiring line and a single transparent electrode to be connected to the wiring line. Since the insulating film and the insulating film are arranged, the density of the wiring line is not so high at this step, but the density of the wiring line is substantially higher when connected to the transparent electrode through the anisotropic conductive rubber. Can be higher. Further, since the conductor width of the wiring line is wider than the conductor width of the transparent electrode, it is conceivable that a plurality of transparent electrodes may face one wiring line. Except for a single transparent electrode that should be connected to the line, it is insulated from the wiring line, so that a plurality of transparent electrodes are not short-circuited via the wiring line.

(f) Embodiment FIG. 1 shows a basic part of an LCD panel mounting substrate according to an embodiment of the present invention. FIG. 1 (A) is a sectional view, FIG. 1 (B) is a transparent electrode pattern of the LCD panel, The same figure (C)
Shows wiring line patterns of the wiring board.

The wiring board 2 has a multi-layered structure of three layers, and each of the upper, middle, and lower wiring boards 2a, 2b, 2c has a stepped structure at its end. The wiring line 20 on the wiring substrate to be connected to the transparent electrode of the LCD panel is divided into three blocks, and the wiring lines 20a, 20b, 20c of each block are exposed at the step portions P1, P2, P3, respectively. . The wiring lines 20a, 20b, 20c of each block are slightly displaced from each other, and the mutual pitch is set to t,
Moreover, the pitch of the wiring lines in the block is set to l (l> t). In order to facilitate understanding, the conductor width of the wiring line 20 in this embodiment is set to be quite small.

The pitch of the transparent electrodes of the LCD panel 1 is set to the same size as the wiring line pitch t of the wiring board. In this embodiment, the transparent electrode 10 is divided into three blocks 10a, 1
The position of the transparent electrode end of each block is aligned with the step of the wiring board. The transparent electrode 10a of the first block corresponds to the wiring line 20a of the first block formed on the uppermost step P1, and the second block transparent electrode 10b is formed on the second step P2 of the middle step. Corresponding to the wiring line 20b of the block. The transparent electrode 10c of the third block is the third electrode formed on the lower step P3.
Corresponds to the wiring line 20c of the block. Three anisotropic conductive rubbers 3a, 3b, 3c are arranged between the wiring board 2 and the LCD panel 1 having the above-mentioned configuration. The first anisotropic conductive rubber 3a is arranged at the position of the uppermost step P1, and the second anisotropic conductive rubber 3b is located at the middle step P2.
Will be placed in the position. The third anisotropic conductive rubber 3c
Is arranged at the position of the lower step portion P3. By arranging the anisotropic conductive rubber in this manner, the transparent electrode 10a of the first block and the wiring line 2 of the first block are arranged.
0a is connected, and the transparent electrode 10b of the second block and the wiring line 20b of the second block are connected. Further, the transparent electrode 1 of the third block is formed by the anisotropic conductive rubber 3c.
0c is connected to the wiring line 20c of the third block.

As in the above-described configuration, the wiring line pitch in the wiring board portion connecting the wiring board 2 and the LCD panel 1 is substantially L.
Since it is equal to the pitch t of the transparent electrodes of the CD panel 1,
Even if there is a limitation on the pitch spacing of the wiring lines on the wiring board 2 and the conductor width of the wiring lines, the pitch of the wiring lines in the portion connected to the LCD panel is substantially improved. Therefore, the resolution of the LCD panel can be easily increased.

As shown in FIG. 1B, the transparent electrode 10 is used in this example.
10a, 10b, 10c, the tip of the transparent electrode for each block is aligned with each step of the wiring substrate 2. However, such a pattern is not always necessary.
On the CD panel side, the tips of the transparent electrodes 10 can all be arranged in the same line.

FIG. 2 shows another structure.

In this example, the wiring board portion connecting the wiring board 2 and the LCD panel 1 is formed at a position other than the end portion of the wiring board. In this example, the upper wiring board 2a is used to form the step.
It is hollowed out to expose the wiring surface of the lower wiring board 2c. Even in this case, the wiring lines 20a and 20b of the two blocks having the pitch t are formed on the two step portions P1 and P2, respectively, as shown in FIG. This example shows an example using a two-layered multilayer substrate.

FIG. 3 shows still another structural example. In this example, a double-sided wiring board is used as the wiring board 2, and the wiring board and the LCD are
Another board 2d is adhered to the wiring board portion for connecting to the panel. When the board 2d is adhered to the bottom of the double-sided wiring board with its ends aligned, and the portion 2a 'in the drawing is cut out, the stepped structure as shown can be obtained. At this time, the wiring pattern formed on the back surface of the substrate 2a 'remains on the step P2 (the substrate 2d is adhered). Therefore, when the wiring patterns on the front surface and the back surface of the substrate 2a are displaced from each other at an interval of t, two step portions P1 and P1 are formed when the substrate structure shown in the drawing is obtained.
As shown in FIG. 1 (C), the wiring lines 20a and 20b of two blocks having a pitch of t are formed in 2 respectively.

FIG. 4 shows still another structural example. Also in this example, a double-sided wiring board is used as the wiring board 2, and the wiring board and the LCD are used.
Another substrate 2d is adhered to the wiring board portion that connects the panel. The difference from the structure example shown in FIG. 3 is that a part connected to the LCD panel is formed in the middle of the substrate as in the structure example shown in FIG. Similar to the structure example shown in FIG. 3, this structure can be easily formed by adhering the substrate 2d with the ends aligned with the lower part of the double-sided wiring substrate and cutting out the portion 2a 'in the figure.

By the way, in the structure of the basic portion described above, the conductor width of the wiring line 20 is set to be considerably small in order to facilitate understanding, but in reality, as described above, the conductor width of the wiring line is transparent. It is considerably larger than the electrode width.
Therefore, as shown in FIG. 5, the transparent electrode 100a positioned immediately above the wiring line 20 via the wiring line 20.
~ 100d will be in a short circuit state. The figure is a cross-sectional view of the substrate viewed from the end face direction.

FIGS. 6 (A) to 6 (C) show an embodiment of the present invention and show a specific structure for eliminating the above-mentioned inconvenience.

The embodiment shown in FIG. 6 (A) is an example in which an insulating film 4 in which necessary portions are opened is printed on the wiring line 20. Printing is performed by screen printing. FIG. 7 shows a substrate structure diagram using this insulating film 4. As shown in the figure, the transparent electrodes 100a, 100
Insulation is placed between c and 100d and the wiring line 20, and only the transparent electrode 100b is electrically connected to the wiring line 20.

FIG. 6B is an example in which a resist film 5 is used instead of the insulating film 4 formed by printing. A known photolithography technique is used to set the opening. Also the 6th
FIG. 6C shows a film 6 in which necessary portions are pre-opened.
Shows an example using.

Even if a plurality of transparent electrodes are located on the wiring line 20 by placing an insulating film (including a resist film and a film) selectively opened on the wiring line 20 having a large conductor width as described above, Only one of the transparent electrodes can be electrically connected to the wiring line. Although the insulating film is formed on the wiring line in the embodiment shown in FIG. 6, it may be formed on the transparent electrode. Further, as shown in FIG. 8, an insulating film may be selectively formed on the transparent electrode. At the end position of the transparent electrode 10a, an insulating film 7 is formed on the transparent electrodes 10b and 10c passing through the position, and at the end position of the transparent electrode 10b, on the transparent electrode 10c passing through the position. The insulating film 8 is formed. By doing so, it is possible to prevent the transparent electrodes 10a, 10b, 10c from being electrically connected to each other even if the conductor width of the wiring line is considerably large.

(g) Effect of the Invention As described above, according to the present invention, the wiring board portion connecting the wiring board and the display panel has a substrate structure of a plurality of stages,
Moreover, since the wiring line is divided into multiple blocks and the wiring line of each block is connected to the display panel via anisotropic conductive rubber, even if the conductor width or pitch of the wiring line cannot be reduced, the display There is an advantage that the substantial pattern density of the portion connected to the panel can be reduced, and high-resolution display independent of the pattern density of the wiring board can be realized. Even if the body width of the wiring line is wider than the conductor width of the transparent electrode, the insulating film can prevent a short circuit between adjacent transparent electrodes.

[Brief description of drawings]

FIGS. 1 (A), (B) and (C) are a sectional view, a transparent electrode line pattern diagram and a wiring line pattern diagram of a basic portion of an LCD panel mounting substrate according to an embodiment of the present invention, respectively. 2 to 4 show other structural examples. Further, FIG. 5 is a diagram for explaining an inconvenience when the conductor width of the wiring line is considerably large, and FIGS. 6A to 6C are diagrams showing an embodiment of the present invention for solving the inconvenience, and FIG. FIG. 8 is a diagram showing a substrate structure according to the same embodiment, and FIG. 8 is a diagram showing still another embodiment of the present invention. 9A and 9B are a plan view and a front view of a conventional display panel mounting board, respectively. 1 ... LCD panel, 2 ... wiring board, 3 ... anisotropic conductive rubber, 10 ... transparent electrode, 20 ... wiring line, P1 to P3 ... step section.

Claims (1)

[Claims] 1. When a display panel having a plurality of X-direction transparent electrodes and Y-direction transparent electrodes formed in a thin film on the back surface of the panel by vapor deposition, sputtering or the like is mounted on a wiring board, the wiring lines and the display on the wiring board are displayed. In a display panel mounting substrate configured to connect the transparent electrode of the panel via an anisotropic conductive rubber, a wiring board unit connecting the wiring board and the display panel, and a substrate structure of a plurality of stages, The wiring line on the wiring substrate connected to the transparent electrode is divided into a plurality of blocks, the wiring line of each block is formed in each step portion of the substrate structure of the plurality of steps, between each step portion and the transparent electrode, A transparent electrode that is arranged opposite to each wiring line between the anisotropic conductive rubber and the wiring line on the wiring board or between the anisotropic conductive rubber and the transparent electrode while arranging the anisotropic conductive rubber. A display panel mounting substrate, wherein an insulating film selectively opening a portion of the wiring line facing only a single transparent electrode to be connected is arranged.