JPH0126556B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flexible printed circuit board, and more particularly to a flexible printed circuit board in which a large number of wiring lines are formed on the surface of a film.

For example, a flexible printed circuit board, which has a large number of wiring lines on the surface of a thin resin film, is used to electrically connect a liquid crystal plate terminal and a liquid crystal drive section of a liquid crystal display device or the like. In this case, a large number of liquid crystal plate terminals are arranged very densely in a row on the surface of the glass substrate. On the other hand, the same number of terminal portions are formed on one edge of the flexible printed circuit board so as to be connected to the respective terminals of the liquid crystal board, and these terminal portions are electrically connected to the wiring on the flexible printed circuit board, respectively. ing.

This flexible printed circuit board has one edge in contact with a part of the surface of the glass substrate of the liquid crystal panel, and the terminals arranged there and the terminals on the edge of the flexible printed circuit board are accurately aligned. Soldering is performed using a laser sequentially from one side of the edge of the printed circuit board.

However, when the thin resin film that forms the terminals is soldered one after another starting from one side, the laser heat causes thermal expansion in the gaps between the terminals. , the terminal part and the other liquid crystal board terminal may no longer match from a certain position. In particular, the terminal portion of this type of printed circuit board is extremely narrow, with a width of approximately 100μ and a center-to-center distance between adjacent terminal portions of approximately 200μ.
Therefore, when a relatively wide printed circuit board is used, the number of terminals arranged on the edge of one printed circuit board increases, and the cumulative elongation due to thermal expansion also increases. This causes the inconvenience that it does not fit the terminal at all.

In order to solve this problem, it has been considered to divide the flexible printed circuit board into several parts and reduce the width of one edge of each printed circuit board, but this would result in extremely poor workability.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a flexible substrate having a large number of terminal parts closely arranged on one edge of the film, and to prevent the film from elongating due to heat when these terminal parts are thermally welded to the corresponding circuit board terminals. It is an object of the present invention to provide a flexible substrate that prevents misalignment between a terminal portion and a mating terminal due to such a problem.

Hereinafter, the flexible substrate of the present invention will be described in more detail with reference to preferred embodiments shown in the accompanying drawings.

FIG. 1 shows a flexible substrate 10 according to an embodiment of the present invention. The flexible substrate 10 includes a thin resin film 11, on one surface of which a large number of wiring lines 12a, 12b, 12c, . , 14c, . . . are formed in a dense array. These terminal parts 14a, 14
b, 14c, . . . are the wirings 12a, 12, respectively.
b, 12c. Further, the width of each terminal portion itself is approximately 100μ as described above, and the distance between the centers of the terminal portions is approximately 200μ.

At one end edge 13 of the film 11, the terminal portions 14e and 14f are spaced apart from each other at a widthwise intermediate portion, and a V-shaped portion as shown in FIG. 1 is formed at that portion.
A letter-shaped notch 15 is formed.

On the other hand, in the above embodiment, the liquid crystal plate 20 is used as a counterpart to which such a flexible substrate 10 is attached.
is shown in FIG. This liquid crystal plate 20 has a display-side glass substrate 20a protruding from its upper end, and transparent conductor terminals 21a, 21b, 21c extending from electrodes within the liquid crystal plate 20 on the back surface of the protrusion.
...is arranged and formed. Terminal portion 14 formed at one end edge of the flexible substrate 10 described above
a, 14b, ... and terminals 21a, 21 of the liquid crystal plate 20
b, . . . are designed in advance to correspond to each other in terms of position when one end edge 13 of the flexible substrate 10 comes into contact with the terminal forming surface of the liquid crystal plate 20.

Such a flexible substrate 10 is a liquid crystal panel 20.
Terminal portions 14a, 14b, . . . on one end edge 13
When attached by soldering to the liquid crystal plate terminals 21a, 21b, 21c,..., the terminal part 14a at one end
The film 11 thermally expands and stretches in its width direction due to the heat generated when the film 11 is sequentially soldered. Then, if the cumulative elongation due to welding of the terminal part from one side part to a distance l is Δx, this Δx is absorbed by the notch 15 as shown in FIG. It is possible to maintain a state in which the terminal portion 14e that has crossed the line accurately matches the other terminals 21e, . . . .

In the above embodiment, the other terminal to which the terminal portion of the flexible board is connected was formed on the liquid crystal board, but the present invention is not limited to this liquid crystal board, and can be applied to various circuit boards. Applicable to

As explained above, according to the flexible substrate of the present invention, the elongation of the film that occurs when the terminal portions arranged densely on one edge of the flexible substrate are sequentially heat-welded to the corresponding mating terminals from one side of the flexible substrate. Misalignment between the terminal portion and the corresponding terminal on the other party can be prevented. Therefore, even if the flexible substrate has a relatively large width, it is only necessary to perform alignment once (aligning the terminal part with the corresponding terminal), and there is no need to reposition the unwelded terminal part during heat welding as in the conventional method. There is no need for any modification work, and continuous soldering is possible with great efficiency. Further, various shapes of such a notch are possible, but as long as the end edge is partially cut out, the same effect can be obtained, and therefore, it should not be limited to this shape. Further, it is preferable that the number and position of the notches are appropriately selected depending on the coefficient of thermal expansion of the film used and the arrangement density of the terminals.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing a flexible substrate according to an embodiment of the present invention attached to a liquid crystal plate, and Fig. 2 is a cut portion that absorbs elongation due to heat during soldering in the flexible substrate shown in Fig. 1. FIG. 10...Flexible board, 11...Film, 12a, 12b, 12c,...Wiring, 13...
... One end edge, 14a, 14b, 14c, ... Terminal part, 15 ... Notch part, 20 ... Liquid crystal plate, 21
a, 21b, 21c...terminals. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] 1. Many wirings formed on the surface of the film,
Terminal portions arranged densely on one end edge of the film and electrically connected to the respective wirings, and at least one cut portion formed between any of the terminal portions on the one end edge of the film, A flexible board in which each of the terminal portions arranged on the one edge of the film is thermally welded and connected to a separate terminal corresponding to a circuit board.