JPH03161996A - Connection of flexible board, and flexible board - Google Patents

Abstract

PURPOSE:To realize easy and sure alignment by forming a window capable of transparently viewing an opponent board, on the side of a conductor pattern where an anisotropic conducting film and a cover film are formed, and equipping said window with a superposition mark with a mark of the opponent board. CONSTITUTION:A conductor pattern 14 formed on a transparent base film 12 of a flexible board 10 is covered with a cover film 16, except an electrode part 18 on the end portion. About half part of tip end side of the electrode part 18 is covered with an anisotropic conducting film 20. The part between the cover film 16 and the anisotropic conducting film 20, e.g. about half part of the rear side of the electrode part 18 is turned into a window 30 being a transparent view part. At the tip end of the flexible board 10 and the part of the window 30, alignment of the conductor pattern 14 of a rigid board 22 and a wiring pattern 26 is performed in this manner, and the alignment is performed in the longitudinal direction of the pattern, thereby facilitating and ensuring alignment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a flexible substrate and a flexible substrate connection method for connecting a flexible substrate in which a conductor pattern is formed on a flexible insulating film to a printed circuit board or the like.

[Conventional technology]

Due to its flexibility, flexible substrates have been used for electrical connections between moving electronic components and between moving electronic components and stationary electronic components, but they are less likely to break down and are more reliable. It is also used for electrical connections between fixed electronic components, and is used in many electronic devices because it allows high wiring density, high wiring density, and miniaturization of devices. In recent years, as high-density wiring becomes possible, an anisotropic conductive film is provided on the electrode part of a flexible board instead of a connector, and the flexible board is directly connected to another board via the anisotropic conductive film. things are starting to be done. 3 to 5 show a conventional method of connecting flexible substrates using an anisotropic conductive film.

The flexible substrate 10 has a conductor pattern 14 made of copper foil formed on a base film 12 made of transparent plastic such as polyester or polyester, and this conductor pattern 14 is covered with a cover film 16 made of plastic.
is covered. The end of the conductor pattern l4 is an electrode section 18 that is not covered with the cover film 16, and an anisotropic conductive film 20 is temporarily attached over almost the entire electrode section 18. The anisotropic conductive film 20 is made of brass material mixed with conductive metal particles, and has adhesive properties when temporarily attached. When thermocompression bonded to the substrate, electricity is conducted only in the thickness direction (vertical direction in FIG. 3). On the other hand, a rigid board 22, which is a mating board to which the flexible board 10 is connected, has a wiring pattern 26 made of copper foil formed on a base material 24.

To connect the flexible substrate 10 and the rigid substrate 22, both substrates 10 and 22 are fixed to a jig attached to a micrometer (not shown) and placed under a microscope, and the end of the flexible substrate 10 is connected to the rigid substrate 22. After overlapping the ends, the operator looks through a microscope and operates a micrometer to match the conductor pattern 14 and the wiring pattern 26 (
(see FIG. 4), the flexible substrate 10 and the rigid substrate 22 are bonded together by thermocompression via the anisotropic conductive film 20 with the two patterns matched, and the conductive pattern 14 and the wiring pattern 2 are bonded together.
6 are electrically connected.

[Problem to be solved by the invention]

However, the anisotropic conductive film 20 does not have very good light transmittance. Therefore, the conductor pattern 14 and the wiring pattern 2
6, it is difficult to check the pattern of the rigid substrate 22 through the anisotropic conductive film 2o. Alignment was achieved based on the presence or absence of external bending between the substrate 10 and the rigid substrate 22. However, alignment between the flexible substrate 1O and the rigid substrate 22 must be performed by partial observation using a microscope, and it is difficult to ensure perfect alignment. Even if a pattern shift occurs due to bending, this cannot be detected. Moreover, the pattern on the flexible substrate 10 is minute, and the distance d between the conductor patterns 14 is only about 75 μrn, whereas the flexible substrate 10 and the rigid substrate 2
The length of the connection part (overlapping part) between the flexible board 10 and the rigid board 22 is approximately 2 mm, and the connection length is large relative to the pattern spacing.If the connection between the flexible board 10 and the rigid board 22 is bent even slightly, it may cause wiring errors such as short circuits. , leading to a decrease in reliability.

The present invention has been made in order to eliminate the drawbacks of the prior art, and provides a method for connecting flexible substrates that can easily and reliably align the conductor pattern of the flexible substrate and the wiring pattern of the mating substrate. Another object of the present invention is to provide a flexible substrate on which the above connection method can be easily implemented.

[Means for Solving the Problems] In order to achieve the above object, a method for connecting a flexible substrate according to the present invention connects a conductor pattern of the flexible substrate to the other party via an anisotropic conductive film provided on the flexible substrate. In a flexible substrate connection method for electrically connecting a wiring pattern of a substrate, the conductor pattern is made to match the wiring pattern of the mating substrate at the tip of the flexible substrate, and the The method is characterized in that the mating board is seen through, the patterns of both boards are superimposed, and the first mark attached to the transparent part and the second mark attached to the mating board are superimposed.

Furthermore, in order to facilitate the implementation of the above connection method, the flexible substrate according to the present invention has a conductor pattern formed on a transparent base film, and a conductor pattern that electrically connects the conductor pattern to a wiring board of a mating board. In a flexible substrate covered with an anisotropic conductive film and a cover film L, a window is formed on a side of the conductive pattern on which the anisotropic conductive film and the cover film are provided, through which the mating substrate can be seen. , is characterized in that it includes a l-th mark provided on the window and superimposed on the second mark made on the mating board.

[Effect]

The flexible board connection method of the present invention constructed as described above not only matches the conductor pattern and wiring pattern at the tip of the flexible board, but also allows the mating board to be seen through the flexible board from a transparent section provided on the flexible board. However, since the patterns are overlapped also in the transparent section, the patterns are overlapped along the length direction of the patterns, and accurate alignment can be easily performed. Moreover, since the first mark made on the transparent part and the second mark made on the mating board are overlapped, not only can patterns be overlapped more easily, but also the conductor pattern on the flexible board can be overlapped with the second mark made on the mating board. Mismatches in correspondence with the wiring pattern of the mating board can be eliminated.

Therefore, it is possible to eliminate short circuits due to pattern misalignment during alignment, improve reliability, and make it possible to form patterns on the flexible substrate with higher density.

Furthermore, since the flexible board of the present invention constructed as described above is provided with a window through which the mating board can be seen, the tip of the flexible board can be easily aligned when aligning the conductor pattern of the flexible board with the wiring pattern of the mating board Not only that, it is possible to align both patterns through the window, and moreover, since the first mark made on the transparent part and the second mark made on the mating board are overlapped,
Each pattern on both boards can be aligned easily and reliably.

(Example) A flexible substrate manufacturing method and a preferred embodiment of the flexible substrate of the present invention will be explained in detail with reference to the accompanying drawings.The same reference numerals are given to the parts corresponding to the parts explained in the above-mentioned prior art. The explanation will be omitted.

FIG. 1 and FIG. 2 are explanatory diagrams of an embodiment according to the present invention.

In these figures, in a flexible substrate 10, a conductive pattern 14 formed on a transparent base film 12 is covered with a cover film 16 except for electrode portions 18 at the ends. Approximately half of the tip side of the electrode portion l8 is covered with the anisotropic conductive film 20. Then, between the cover film l6 and the anisotropic conductive film 20, that is, the electrode part 18
Approximately half of the rear side is a window 30 which is a see-through part that does not cover the electrode part l8, and from above the base film 12, the other party located below the flexible substrate 10 can be seen from above the base film 12 through this window 30. The rigid substrate 22, which is a substrate, can be seen through.

The connection between the flexible substrate 10 and the rigid substrate 22 of the embodiment configured as described above is performed as follows.

(2) As in the conventional case, the flexible substrate 10 and the rigid substrate 22 are mounted on a jig attached to a micrometer and placed under a microscope (both not shown).

■ Inject light from above in FIG. 1, that is, from above the flexible substrate 10, look through a microscope and operate a micrometer to move the electrode section 18 of the flexible substrate 10 above the rigid substrate 22, and move the flexible substrate 10
The conductor pattern 14 and the wiring pattern 26 of the rigid board 22 are made to match at the tip thereof (see FIG. 2).

(2) While looking through a microscope, look through the rigid board 22 from above the flexible board 10 through the window (see-through part) 30, and observe whether there is any misalignment between the patterns on both boards.

■ If there is a misalignment in the overlapping patterns as shown in Figure 2, operate the micrometer to rotate the jig to match the patterns at the tip of the flexible substrate 10, and then place the rigid substrate at the window 30. 22 wiring patterns 26 and the conductor pattern 14 of the flexible substrate 10 are overlapped.

■Once the overlapping (alignment) of the above patterns is completed, the flexible substrate 1o and the rigid substrate 22
The conductor pattern l4 and the wiring pattern 26 are electrically connected via the anisotropic conductive film 2o.

In this embodiment, the flexible substrate 10
A transparent window 30 is provided at the top of the flexible substrate 10 and the wiring pattern 26 is aligned with the conductive pattern 4 of the rigid substrate 22 at the tip of the flexible substrate 10 and the window 30, so alignment is achieved in the longitudinal direction of the pattern. As a result, alignment 1 can be performed easily, reliably, and accurately. Therefore, it is possible to eliminate shows 1 and the like caused by misalignment of overlapping patterns when aligning the flexible substrate and the rigid substrate 22, thereby improving reliability. Moreover, since the alignment 1 is made easier, the workability of the connection work between the flexible board 10 and the rigid board 22 is improved, and the connection work can be performed quickly. And the tip of the flexible substrate 10,
Since the patterns are superimposed at two points with the window 30 provided at a position away from the tip, more accurate alignment is possible. As a result, it becomes possible to form the pattern of the flexible substrate 10 with higher density, and it is possible to miniaturize and increase the density of electronic equipment.

Furthermore, the window 30 of the embodiment has an anisotropic conductivity 11i 2 0
Since it is provided at the tip of the electrode part 18 and formed between the anisotropic conductive film 20 and the cover film 16, there is no need to increase the number of steps or change the process when manufacturing the flexible substrate 10. Further, in the embodiment, since the light is directed from the flexible substrate 10 side to see through the rigid substrate 22, even if the rigid substrate 22 is opaque, the conductor pattern 14 and the wiring pattern 26 are Alignment can be performed easily and reliably.

Note that it is desirable that the window 30 be formed between the cover film 16 and the anisotropic conductive film 20 as in the embodiment, but
The anisotropic conductive film 20 may be provided on the cover film 16 side of the electrode section 18, and the tip of the electrode section 1 may be used as a viewing window. Furthermore, in the embodiment described above, the anisotropic conductive film 20 is approximately half the length of the electrode portion 18, but the anisotropic conductive film 20 is It only needs to be long enough to ensure continuity. and,
The viewing window may be formed by cutting out a part of the cover film 16 or the anisotropic conductive film 20. Further, a first mark such as a figure is attached to the transparent window 30, and a second mark corresponding to the first mark is attached to the mating board when the flexible board and the mating board are joined at the correct position. may be added.

Furthermore, if the first and second marks are colored, joining becomes even easier.

〔Effect of the invention〕

As explained above, according to the connection method of the present invention, not only the conductor pattern and the wiring pattern at the tip of the flexible board match, but also the connection of the mating board through the flexible board from the transparent part provided on the flexible board. Since both patterns are superimposed by seeing through, and the first mark made on the see-through part is superimposed with the second mark made on the mating board, the patterns are overlapped in the length direction of the pattern. It is possible to easily achieve accurate alignment. Therefore, it is possible to eliminate short circuits due to pattern misalignment during alignment, improve reliability, and make it possible to form patterns on the flexible substrate with higher density.

Moreover, since the flexible board of the present invention is provided with a window through which the mating board can be seen, when aligning the conductor pattern of the flexible board and the wiring pattern of the mating board, not only the tip of the flexible board but also the wiring pattern of the mating board can be aligned. Alignment of both patterns can be performed by looking through the mating board through the window, and a first mark is placed on the transparent part to overlap the second mark made on the mating board during alignment, making it possible to use the connection method described above. It can be easily implemented.

[Brief Description of the Drawings] Figure 1 is a sectional view of a flexible board according to an embodiment of the present invention, Figure 2 is a plan view illustrating a connection method according to an embodiment of the invention, and Figure 3 is a conventional flexible board. FIG. 4 is a sectional view of the board, FIG. 4 is a plan view illustrating a conventional flexible substrate connection method, and FIG. 5 is an explanatory diagram of a connection state by the conventional connection method. 1 0-1---Flexible board, ]-2-1111 base film, 14-11 conductor pattern, 1
6 --- one cover film, 20 --- one anisotropic conductive film, 2 2 --- one mating substrate (rigid substrate), 2 6 --- one wiring pattern, 3 0-
--One window (transparent part).

Claims (2)

[Claims] (1) In a flexible substrate connection method in which a conductor pattern of the flexible substrate and a wiring pattern of a mating substrate are electrically connected via an anisotropic conductive film provided on the flexible substrate, the tip of the flexible substrate The conductor pattern is made to match the wiring pattern of the mating board, and the mating board is seen through a transparent part formed on the flexible board to overlap the patterns of both boards. A method for connecting flexible circuit boards, characterized in that the mark and a second mark attached to the mating board are overlapped. (2) In a flexible substrate in which a conductor pattern formed on a transparent base film is covered with an anisotropic conductive film and a cover film that electrically connect the conductor pattern to a wiring pattern of a mating board, the conductor pattern is A window through which the mating substrate can be seen is formed on the side of the pattern where the anisotropic conductive film and the cover film are provided, and the window is provided in the window and overlapped with a second mark attached to the mating substrate. A flexible substrate comprising a first mark.