JP2003069164A - Flexible wiring circuit board for flat panel display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible wiring circuit board for flat panel displays that can easily and reliably connect a plurality of terminal sections with appropriate dimension stability even if no tolerance is set in designing, and can effectively prevent disconnection of each wiring pattern since bending resistance properties are appropriate even if the flexible wiring circuit board is bent to a flat panel display. SOLUTION: At a connection section 8 of a display side formed at the front end of a flexible wiring circuit board 1, a plurality of display side terminal sections 10 that are aligned and arranged in a fine pitch, and a strip of reinforcing metal foil 12 are laminated and formed along the width direction of the flexible wiring circuit board 1 on the rear of a base insulating layer 2 so that they overlap each other in the thickness direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flexible printed circuit board for a flat panel display, and more specifically, a flexible printed circuit board for a flat panel display used for connection with a flat panel display such as a plasma display, an EL display and a liquid crystal display. Regarding

[0002]

2. Description of the Related Art Flat panel displays such as plasma displays, EL displays and liquid crystal displays are light, thin, lightweight and compact screen display devices.
For example, the demand for various electronic and electric devices such as a personal digital assistant (PDA), a car navigation device, and a wall-mounted television is increasing more and more.

Such a flat panel display is usually connected to an external circuit such as a control circuit via a flexible wiring circuit board. In recent years, the flat panel display and the flexible wiring circuit board are anisotropically connected to each other. A method of connecting using a conductive film (ACF) is widely practiced.

That is, since a large amount of information needs to be transmitted quickly in the flat panel display, the connection between the flat panel display and the flexible printed circuit board is performed by the flat panel display.
A large number of electrodes are formed at a fine pitch, and a large number of wiring patterns and terminal portions are formed at a fine pitch on the flexible printed circuit board to correspond to the large number of electrodes. It is necessary to surely connect the electrode and the large number of terminal portions for each electrode and between the terminal portions.

Therefore, by using an anisotropic conductive film capable of conducting only in the pressurizing direction,
Between the large number of electrodes of the flat panel display and the large number of terminal portions of the flexible printed circuit board, along the direction in which they are formed, intervening in a strip shape and then thermocompression-bonding each electrode and The terminals are connected together.

When the flat panel display and the flexible printed circuit board are connected by such an anisotropic conductive film, a large number of electrodes and a large number of terminals formed at a fine pitch are provided for each electrode and between the terminals. In addition, since the connection can be made easily and surely at one time, the productivity can be remarkably improved.

[0007]

[Problems to be Solved by the Invention] However, in this way,
When a large number of electrodes of a flat panel display and a large number of terminals of a flexible printed circuit board are connected using an anisotropic conductive film, it is necessary to perform thermocompression bonding of these electrodes. Even a slight change in the dimension of the circuit board may cause a deviation in the pitch between the terminal portions formed with a fine pitch, resulting in a decrease in connection reliability.

Therefore, in the flexible printed circuit board used for such a flat panel display,
At the time of designing, it is unavoidable to set the pitch tolerance (correction value) between each terminal part that allows for such dimensional changes. Therefore, it is possible to design a fine pitch wiring pattern with high accuracy. It is hindered.

When the flexible wiring circuit board is bent with respect to the flat panel display at the time of assembling after connecting the flat panel display and the flexible wiring circuit board, the portions where they are connected, especially the wiring. In some cases, stress concentration occurs at the exposed end of the pattern, resulting in disconnection of each wiring pattern.

The present invention has been made in view of such circumstances, and an object thereof is to achieve good dimensional stability without setting a tolerance at the time of designing, and to easily and easily connect a plurality of terminal portions. A flat panel display that can be reliably connected to each other, has good bending resistance even when a flexible printed circuit board is bent with respect to a flat panel display, and can effectively prevent disconnection of each wiring pattern. To provide a flexible printed circuit board for use.

[0011]

In order to achieve the above object, the present invention comprises a base insulating layer and a conductor layer formed on the surface of the base insulating layer and formed of a plurality of wiring patterns. A flexible printed circuit board for a flat panel display, in which a connecting portion for connecting a plurality of electrodes formed in a panel display and a plurality of the wiring patterns are formed, wherein the connecting portion has a plurality of Corresponding to the wiring pattern, a plurality of terminal portions for connecting to each of the plurality of electrodes are provided in line at a predetermined pitch, and a plurality of terminal portions are provided on the back surface of the base insulating layer in the connection portion. It is characterized in that a strip-shaped metal reinforcing layer is provided along the alignment direction of the terminal portions so as to overlap with the terminal portions in the thickness direction.

According to such a flexible printed circuit board for a flat panel display, a plurality of terminal portions,
Even if the plurality of electrodes of the flat panel display are thermocompression bonded using the anisotropic conductive film, the strip-shaped metal reinforcing layer supports the plurality of terminal portions from the back surface of the insulating base layer during the thermocompression bonding. Therefore, it is possible to effectively prevent a dimensional change in the pitch between the terminal portions. for that reason,
At the time of designing, each terminal can be connected easily and surely without setting the tolerance of the pitch between each terminal, so that an accurate fine-pitch wiring pattern can be designed. .

Further, even after the flat panel display and the flexible wiring circuit board for the flat panel display are connected to each other and the flexible wiring circuit board for the flat panel display is bent with respect to the flat panel display, the strip-shaped metal reinforcing layer forms a base. Since the back surface of the insulating layer supports a plurality of terminal parts to which a plurality of electrodes are respectively connected, it is possible to mitigate stress concentration at the connection parts, which results in disconnection of each wiring pattern. Can be effectively prevented.

Further, the flexible printed circuit board for a flat panel display according to the present invention comprises a cover insulating layer covering the conductor layer, and the connecting portion is formed so that the conductor layer is exposed from the cover insulating layer. It is preferable that the metal reinforcing layer is provided so as to overlap the insulating cover layer in the thickness direction.

Thus, if the metal reinforcing layer is provided so as to overlap the insulating cover layer in the thickness direction, in that portion, the metal reinforcing layer in the thickness direction of the flexible printed circuit board for flat panel display, Since the four layers of the base insulating layer, the conductor layer and the cover insulating layer overlap, the mechanical strength can be further improved. Therefore, when the flexible printed circuit board for a flat panel display is bent with respect to the flat panel display, in particular, disconnection of the wiring pattern at the end of the exposed conductor pattern can be more effectively prevented.

Further, in the flexible printed circuit board for flat panel display of the present invention, the connecting portion is provided at an end portion of the flexible printed circuit board for flat panel display, and the metal reinforcing layer is formed by the base insulation. It is preferably provided more inside than the edge portion of the layer.

In the connection portion provided at the end portion of the flexible printed circuit board for flat panel display, the metal reinforcing layer is the same as the edge portion of the insulating base layer, or
If it is provided so as to project outward, there is a risk that the metal reinforcing layer and the conductor layer will be electrically connected to each other via the outside of the edge portion of the insulating base layer, and each terminal part will be short-circuited. .

However, in this way, if the metal reinforcing layer is provided inside the edge portion of the insulating base layer, the conductor is thus provided outside the edge portion of the insulating base layer. It is possible to effectively prevent the terminals from short-circuiting by being electrically connected to the layer, and it is possible to improve the connection reliability.

[0019]

1 is a plan view showing an embodiment of a flexible printed circuit board for a flat panel display of the present invention, FIG. 2 is a bottom view thereof, and FIG. 3 is a side sectional view thereof. Note that, in FIGS. 1 to 3, adhesive layers 16, 19 and 20, which will be described later, are omitted.

1 and 2, the flexible wiring circuit board 1 for a flat panel display (hereinafter, abbreviated as the flexible wiring circuit board 1) is a display side wiring portion 1 having a substantially wide rectangular shape in a plan view.
a, the external wiring portion 1b having a substantially narrow rectangular shape having a width narrower than that of the display wiring portion 1a, and between them, the width becomes narrower from the display wiring portion 1a toward the external wiring portion 1b. The substantially trapezoidal relay wiring portion 1c formed in a taper shape is integrally formed, and is formed as a flexible thin plate shape. A relay opening 1d (only shown in FIGS. 1 and 2) for connecting a relay element or the like is formed between the external wiring portion 1b and the relay wiring portion 1c.

As shown in FIG. 3, the flexible printed circuit board 1 includes a base insulating layer 2, a conductor layer 3 formed on the surface of the base insulating layer 2, and a conductor layer 3 thereof.
And an insulating cover layer 4 for covering the conductor layer 3
1 is composed of a plurality of wiring patterns 5, as shown in FIGS.

The insulating base layer 2 is in the form of a thin film, forms the outer shape of the flexible printed circuit board 1, and supports the conductor layer 3 and the insulating cover layer 4.

As shown in FIGS. 1 and 2, each wiring pattern 5 has one end extending to the front end edge portion 6 of the display side wiring portion 1a and the other end being outside on the surface of the insulating base layer 2. The wiring portions 1b extend to the rear end edge portion 7 and are arranged in parallel in a widthwise direction with a predetermined pitch therebetween. That is, in the display-side wiring portion 1a, a large number of such wiring patterns 5 are provided so as to correspond to the large number of electrodes 22 (see FIG. 6) formed in the flat panel display 21. The wiring patterns 5 are arranged in parallel and at a fine pitch in the width direction, and in the relay wiring portion 1c, they are arranged so as to be grouped together via the relay opening 1d, and in the outer wiring portion 1b. The conductor pattern is formed on the insulating base layer 2 as a conductor pattern so that a predetermined number of the collected wiring patterns 5 are wired in parallel.

The insulating cover layer 4 is formed on the surface of the insulating base layer 2 so as to cover the conductor layer 3, and the front end of the flexible wiring board 1 has a plan view thereof. The base insulating layer 2 and the wiring patterns 5 of the front edge portion 6 are formed up to the front of the front edge portion 6, and the base insulating layer 2 of the rear edge portion 7 and The wiring pattern 5 is formed so as to be exposed before the rear end edge portion 7. The insulating cover layer 4 is spaced from the front end edge portion 6 along the longitudinal direction of the wiring pattern 5 by an interval of 1 to 7 mm, and further an interval of 3 to 5 mm (an interval indicated by S1 in FIG. 1). It is preferably formed, and 1 to 6 m from the rear edge 7 along the longitudinal direction of the wiring pattern 5.
It is preferable that they are formed at a distance of m, and further at an interval of 2 to 4 mm (the interval indicated by S2 in FIG. 1).

Then, this flexible printed circuit board 1
Has a flat panel display 21 at its front end.
A display-side connecting portion 8 for connecting to the display is provided, and an external-side connecting portion 9 for connecting to an external circuit such as a control circuit is provided at a rear end portion thereof.

The display-side connecting portion 8 is formed on the front end portion of the flexible printed circuit board 1 by exposing the conductor layer 3 from the insulating cover layer 4 as described above, and is formed on the flat panel display 21. The display-side terminal portion 10 is provided as a terminal portion for connecting each of the plurality of electrodes 22 (see FIG. 6) and the plurality of wiring patterns 5 respectively.

That is, in this flexible printed circuit board 1, each wiring pattern 5 exposed from the insulating cover layer 4 at the front end thereof, that is, the tip of each wiring pattern 5 becomes the display-side terminal portion 10 as it is. Therefore, in the display-side connection portion 8, the display-side terminal portions 10 corresponding to the wiring patterns 5 are arranged at a predetermined fine pitch in the width direction of the flexible wiring board 1. It is arranged.

Incidentally, such a display side terminal portion 1
0 is usually provided in the range of 200 to 300 lines, and in the case of higher density, 0 to 300 lines, and the line and space (terminal width / between terminals) thereof is 100.
.About.200 .mu.m / 100 to 200 .mu.m, and in the case of higher density, it is formed as 50 to 100 .mu.m / 50 to 100 .mu.m. Each wiring pattern 5 formed on the display-side wiring portion 1a has the same number and line and space.

The external connection portion 9 is formed at the rear end portion of the flexible printed circuit board 1 by exposing the conductor layer 3 from the insulating cover layer 4 as described above, and is used for a control circuit or the like. An external-side terminal portion 11 for connecting each electrode (not shown) formed in the external circuit and each wiring pattern 5 is provided.

That is, in this flexible printed circuit board 1, each wiring pattern 5 exposed from the insulating cover layer 4 at the rear end thereof, that is, the rear end of each wiring pattern 5 is directly connected to the external terminal portion 11. Therefore, in the external-side connecting portion 9, each external-side terminal portion 11 corresponding to each wiring pattern 5 is formed.
Are arranged so as to be arranged at a predetermined pitch in the width direction of the flexible wiring board 1.

And this flexible printed circuit board 1
Then, the insulating base layer 2 in the display side connecting portion 8
A reinforcing metal foil 12 as a metal reinforcing layer is provided on the back surface of the above, and a reinforcing film 13 is provided on the back surface of the insulating base layer 2 in the external connection portion 9.

That is, the reinforcing metal foil 12 is formed on the back surface of the insulating base layer 2 at the front end of the flexible printed circuit board 1 in the width direction of the flexible printed circuit board 1 (that is, the alignment direction of the display-side terminal portions 10). Is formed in a strip shape along the above, and is provided so as to overlap each display-side terminal portion 10 in the thickness direction. More specifically, the reinforcing metal foil 12 is provided on the back surface of the insulating base layer 2 in the widthwise front edge portion 14 thereof.
Is arranged more inside than the front end edge portion 6 of the insulating base layer 2, and the rear end edge portion 15 in the width direction thereof is arranged so as to overlap the cover insulating layer 4 in the thickness direction. It is formed in a strip shape over the entire width direction of the substrate 1.

More specifically, this reinforcing metal foil 1
2 has a width (width indicated by W in FIG. 2) of 1 to 7 m
m, more preferably 3 to 5 mm, and 0.5 to 4 mm from the front edge 6 of the insulating base layer 2.
Furthermore, it is preferable that they are arranged on the inner side with an interval of 1 to 2 mm (an interval indicated by S3 in FIG. 2), and 0.5 in the thickness direction with the insulating cover layer 4.
It is preferable that they are arranged so that an overlapping portion (a portion indicated by L in FIG. 1) of ˜4 mm, and further, 1 to 2 mm is formed.

The reinforcing film 13 is formed on the back surface of the insulating base layer 2 at the rear end of the flexible printed circuit board 1 in the width direction of the flexible printed circuit board 1 (that is, the alignment direction of the external terminal portions 11). Is formed in a strip-like shape along the above, and is formed so as to overlap each external terminal portion 11 in the thickness direction. The reinforcing film 13 has a predetermined width on the back surface of the insulating base layer 2 from a position where one end side thereof overlaps the insulating cover layer 4 in the thickness direction to the rear end edge portion 6 of the flexible printed circuit board 1. Has been formed.

Next, a method for manufacturing the flexible printed circuit board 1 will be briefly described with reference to FIGS. 4 and 5. 4 and 5, the cross section along the longitudinal direction of the wiring pattern 5 is a side cross-sectional view in the "X-axis direction" (the direction indicated by the arrow X in FIG. 1), and the width of the flexible printed circuit board 1 is also shown. The cross sections along the direction (alignment direction of the display-side connecting portion 8) are respectively shown as vertical cross-sectional views in the “Y-axis direction” (direction indicated by arrow Y in FIG. 1).

In order to manufacture this flexible printed circuit board 1, first, an insulating base layer 2 is prepared as shown in FIG. The insulating base layer 2 has insulating properties and flexibility, and is not particularly limited, but examples thereof include polyimide resin, acrylic resin, polyether nitrile resin, polyether sulfone resin, polyethylene terephthalate resin, polyethylene naphthalate. resin,
A resin film such as polyvinyl chloride resin is used. A polyimide resin film is preferably used. The thickness of this resin film is, for example, 12.
It is preferably 5 to 125 μm, and more preferably 12.5 to 25 μm.

Next, in this method, as shown in FIG. 4B, the adhesive layer 16 is formed on the surface of the insulating base layer 2.
The conductor layer 3 is laminated via the.

As an adhesive for forming the adhesive layer 16,
Although not particularly limited, for example, heat of polyimide adhesive, epoxy adhesive, epoxy-nitrile butyl rubber adhesive, epoxy-acrylic rubber adhesive, acrylic adhesive, butyral adhesive, urethane adhesive, etc. A curable adhesive, for example, a thermoplastic adhesive such as a synthetic rubber-based adhesive, for example, an acrylic pressure-sensitive adhesive which is a pressure-sensitive adhesive is used, and preferably a polyimide-based adhesive, an epoxy-based adhesive, or an epoxy. -Nitrile butyl rubber adhesive, epoxy-acrylic rubber adhesive, acrylic adhesive are used. The thickness of the adhesive layer 16 is, for example, 5 to 35 μm, preferably 5 to 20 μm.

The conductor layer 3 is electrically conductive and is not particularly limited. For example, copper, chromium, nickel, aluminum, stainless steel, copper-beryllium, phosphor bronze, iron-nickel, and A metal foil such as an alloy thereof is used, and preferably a copper foil is used. The thickness is, for example, 5 to 35 μm, preferably 5 to 18 μm.

In order to stack the conductor layer 3 on the surface of the insulating base layer 2 with the adhesive layer 16 interposed, for example,
The adhesive layer 16 is laminated on the surface of the insulating base layer 2 by applying a solution adhesive and drying it, or by sticking a film adhesive on the surface of the adhesive layer 16. After the conductor layers 3 made of metal foil are superposed on each other, they may be thermocompression bonded at a predetermined temperature and pressure.

In order to stack the conductor layer 3 on the surface of the insulating base layer 2, for example, a solution resin is applied to a metal foil and dried, or a film resin having an adhesive property is used. The conductor layer 3 may be directly laminated on the surface of the insulating base layer 2 without interposing the adhesive layer 16 by, for example, adhering to the metal foil.

Next, in this method, as shown in FIG. 4C, the conductor layer 3 is patterned to form a plurality of wiring patterns 5. The conductor layer 3 may be patterned by a known method, for example, a subtractive method is used.

In the subtractive method, first, as shown in FIG.
As shown in (a), a photoresist 17 is laminated on the conductor layer 3. The photoresist 17 may be laminated by, for example, laminating a dry film resist by a known method. Next, as shown in FIG. 5B, the photoresist 17 is exposed through a photomask 18 corresponding to a predetermined pattern, and then the photoresist 17 is developed as shown in FIG. 5C. . The exposure and development of the photoresist 17 may be a known method, and the photoresist 17 is developed into a predetermined resist pattern due to the difference in solubility of the developing solution between the exposed portion and the unexposed portion.

Then, as shown in FIG. 5D, the conductor layer 3 is etched. The metal foil 1 may be etched by a known wet etching method using an etching solution, and then the photoresist 17 is removed by a known method to form a plurality of conductive layers 3 as shown in FIG. 4C. It can be formed as the wiring pattern 5.

In addition to the subtractive method described above, a known patterning method such as an additive method or a semi-additive method may be used for patterning the conductor layer 3 depending on the purpose and application. .

Then, in this method, as shown in FIG. 4D, the insulating cover layer 4 is formed on the surface of the insulating base layer 2 in a state of covering the conductive layer 3 composed of a plurality of wiring patterns 5. Form. As the insulating cover layer 4, the same resin as described above is used, and preferably a polyimide resin is used. The insulating cover layer 4 may be formed by applying or printing a solution resin, drying and curing it, or by sticking a film resin. Moreover,
After applying the solution of the photosensitive resin, it may be patterned into a predetermined shape by exposure and development.

The insulating cover layer 4 thus formed has a thickness of, for example, 12.5 to 125 μm.
m, preferably 12.5 to 25 μm.

In forming the insulating cover layer 4, as described above, the wiring patterns 5 are exposed at the front end and the rear end of the flexible wiring board 1,
The display-side connecting portion 8 and the external-side connecting portion 9 are formed respectively.

The display-side connecting portion 8 and the external-side connecting portion 9 are formed at the same time when the insulating cover layer 4 is formed, for example, in the case of printing a solution resin or patterning a photosensitive resin. In addition, when the solution-like resin is applied over the entire surface or when the film-like resin is adhered, the insulating cover layer is formed by a known method such as drilling, punching, laser processing, or etching. 4 may be formed by opening the front end and the rear end.

In this method, as shown in FIG. 4E, the reinforcing metal foil 12 is laminated on the back surface of the insulating base layer 2 in the display-side connecting portion 8 and the external-side connecting portion 9 is formed. The reinforcing film 13 is laminated on the back surface of the insulating base layer 2.

As the reinforcing metal foil 12, the same metal foil as described above is used, and preferably copper foil is used. The thickness is, for example, 10 to 35 μm, preferably 18 to 35 μm.
It is 35 μm. The formation of such a reinforcing metal foil 12 is
For example, the strip-shaped reinforcing metal foil 12 having the above-described predetermined width is prepared, and the base insulating layer 2 is provided with the adhesive layer 19 interposed therebetween.
Along the width direction of the flexible printed circuit board 1 on the back surface of the above-mentioned predetermined portion (that is, with respect to the front end edge portion 6 of the insulating base layer 2) that overlaps with each display-side terminal portion 10 in the thickness direction. It may be laminated on the inner side, that is, the portion overlapping the insulating cover layer 4 in the thickness direction).

As an adhesive for forming the adhesive layer 19,
An adhesive similar to the above-mentioned adhesive is used, and preferably an epoxy adhesive is used. Also, the adhesive layer 1
The thickness of 9 is, for example, 5 to 35 μm, preferably 5 to 35 μm.
It is 20 μm.

To form the reinforcing metal foil 12 on the back surface of the insulating base layer 2 via the adhesive layer 19, for example, a solution adhesive is applied on the back surface of the insulating base layer 2. After applying and drying, or by adhering a film-like adhesive, the adhesive layer 19 is laminated, and the reinforcing metal foil 12 made of a metal foil is superposed on the adhesive layer 19. The thermocompression bonding may be performed at a predetermined temperature and pressure.

As the reinforcing film 13, the same resin film as described above is used, and preferably a polyimide resin film is used. Also, its thickness is, for example,
12.5 to 250 μm, preferably 25 to 250 μm
Is. For the formation of such a reinforcing film 13, for example, a strip-shaped reinforcing film 13 having a predetermined width is prepared, and the reinforcing film 13 is provided on the back surface of the insulating base layer 2 via the adhesive layer 20. Along the width
The above-described predetermined portion that overlaps with each external terminal portion 11 in the thickness direction (that is, from the position where one end side thereof overlaps with the insulating cover layer 4 in the thickness direction to the rear end edge portion 7 of the flexible printed circuit board 1). Layer). The adhesive layer 20 can be formed by the same method with the same adhesive as described above, and the thickness thereof is, for example, 5 to 35 μm, preferably 5 to 20 μm.
m and the reinforcing film 13 is such an adhesive layer 2
The reinforcing film 13 made of a resin film may be superposed on top of 0 and then thermocompression bonded at a predetermined temperature and pressure.

In the flexible printed circuit board 1 thus formed, the external terminals 11 of the external connection portion 9 are connected to the electrodes of the external circuit such as the control circuit, while the external connection terminals 9 are connected to the display side. The display side terminal 10 of the part 8 is the electrode 22 of the flat panel display 21.
(See FIG. 6).

The display side terminal 10 of the display side connecting portion 8 is connected to the electrode 2 of the flat panel display 21.
An anisotropic conductive film 23 is usually used to connect to No. 2 as shown in FIG. The anisotropic conductive film 23 is a polymer film in which the conductive particles 24 are uniformly dispersed in the adhesive 25, and can conduct electricity only in the thickness direction of the film. In FIG. 6, the adhesive layers 16, 1 described above are used.
9 and the like are omitted.

Then, by using such an anisotropic conductive film 23, the display-side terminal 1 of the display-side connecting portion 8 is formed.
In order to connect 0 and the electrode 22 of the flat panel display 21, first, as shown in FIG. 6A, the electrode 22 of the flat panel display 21 and the display side terminal 10 of the display side connecting portion 8 are connected. A band-shaped anisotropic conductive film 23 is interposed therebetween along the width direction of the flexible printed circuit board 1 (alignment direction of the display-side connecting portions 8), and then, as shown in FIG. May be thermocompression bonded. The thickness of the anisotropic conductive film 23 is usually 2
The pressure for thermocompression bonding is, for example, 2 to 4 MPa, though it depends on the type of the anisotropic conductive film 23.
Pressurization and heating may be performed at a temperature of 170 to 220 ° C. Accordingly, the display-side connecting portion 8 and the flat panel display 21 are bonded to each other by the adhesive 25 of the anisotropic conductive film 23.
And the display side terminal 10 and the electrode 22 are electrically connected by the conductive particles 24.

By connecting the display-side terminal 10 of the display-side connecting portion 8 and the electrode 22 of the flat panel display 21 with such an anisotropic conductive film 23, a large number of display-side terminals formed at a fine pitch. 10 and the electrode 22 to each display side terminal 10
Further, it is possible to easily and surely connect each of the electrodes 22 and the electrodes 22 at a time, and it is possible to remarkably improve the productivity.

In the bonding using the anisotropic conductive film 23 as described above, it is necessary to perform thermocompression bonding. Therefore, even if a slight dimensional change of the flexible wiring circuit board 1 occurs at the time of thermocompression bonding, it is caused thereby. , The pitch between the display-side terminals 10 formed at the fine pitch may be deviated, and the connection reliability may be deteriorated.

However, this flexible printed circuit board 1
Then, at the time of thermocompression bonding, since the strip-shaped reinforcing metal foil 12 reliably supports each of the display-side terminals 10 from the back surface of the insulating base layer 2, there is no dimensional change in the pitch between the display-side terminals 10. It is effectively prevented from happening.

Therefore, in the past, in practice, +0.05
Approximately +0.1 dimensional change occurs, and at the time of designing, each display side terminal 10 that allows for such dimensional change
It is unavoidable to set the pitch tolerance (correction value) between the two, and the design of the fine-pitch wiring pattern 5 with high accuracy is obstructed by that amount. However, by using this flexible wiring circuit board 1, It is possible to realize an accurate design of the fine-pitch wiring pattern 5 without setting such a tolerance (correction value).

In this flexible printed circuit board 1, after connecting with the flat panel display 21,
Even when the flexible printed circuit board 1 is bent with respect to the flat panel display 21, the strip-shaped reinforcing metal foil 12 has a plurality of display-side terminals 10 to which a plurality of electrodes 22 are respectively connected from the back surface of the insulating base layer 2.
Since it supports, it is possible to alleviate the stress concentration at the connecting portion. Therefore, the disconnection of each wiring pattern 5 can be effectively prevented.

Moreover, this flexible printed circuit board 1
Then, since the strip-shaped reinforcing metal foil 12 is provided so as to overlap the cover insulating layer 4 in the thickness direction, the reinforcing metal foil 12 and the base in the thickness direction of the flexible printed circuit board 1 at the overlapping portion. Since the four layers of the insulating layer 2, the conductor layer 3, and the insulating cover layer 4 overlap, the mechanical strength can be further improved. Therefore, when the flexible printed circuit board 1 is bent with respect to the flat panel display 21, in particular, disconnection of the wiring pattern 5 at the exposed end portion of the conductor pattern 5 (that is, the front end portion of the insulating cover layer 4) or the like,
It can be prevented more effectively.

Furthermore, this flexible printed circuit board 1
Since the strip-shaped reinforcing metal foil 12 is provided more inside than the front end edge portion 6 of the base insulating layer 2, the reinforcing metal foil 12 covers the outside of the front end edge portion 6 of the base insulating layer 2. The conductive layer 3 is electrically connected through the conductive layer 3 to effectively prevent each display side terminal 10 from being short-circuited. Therefore, it is possible to further improve the connection reliability.

Since the flexible wiring circuit board 1 uses the reinforcing metal foil 12 made of metal foil,
Even when pressure and heat are applied at a temperature of 170 to 220 ° C., strength deterioration is less than that of the resin film, and good support of each display-side terminal 10 is realized.

[0066]

As described above, the flexible printed circuit board for a flat panel display of the present invention has good dimensional stability without setting tolerances at the time of design,
Multiple terminal parts can be connected easily and reliably, and even if the flexible printed circuit board is bent with respect to the flat panel display, the bending resistance is good, and disconnection of each wiring pattern is effectively prevented. be able to.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a flexible printed circuit board for a flat panel display of the present invention.

FIG. 2 is a bottom view of the flexible printed circuit board for the flat panel display shown in FIG.

FIG. 3 is a side sectional view of the flexible printed circuit board for the flat panel display shown in FIG.

FIG. 4 is a process cross-sectional view showing an embodiment of a method for manufacturing a flexible wired circuit board for a flat panel display of the present invention, in which (a) is a step of preparing a base insulating layer and (b) is a base. A step of laminating a conductor layer on the surface of the insulating layer via an adhesive layer, (c) a step of patterning the conductor layer into a plurality of wiring patterns, (d) a state of covering the conductor layer, The step (e) of forming a cover insulating layer on the front surface of the base insulating layer includes forming a reinforcing metal foil on the back surface of the base insulating layer in the display-side connecting portion and forming the base insulating layer in the outer-side connecting portion. The step of laminating and forming the reinforcing film on the back surface of is shown.

5A to 5C are process cross-sectional views of the process of patterning the conductor layer into a plurality of wiring patterns shown in FIG.
Is a step of laminating a photoresist on the conductor layer,
(B) shows a step of exposing the photoresist through a photomask, (c) shows a step of developing the photoresist, and (d) shows a step of etching the conductor layer.

FIG. 6 is a process cross-sectional view showing a process of connecting a display-side terminal of a display-side connecting portion to an electrode of a flat panel display, wherein (a) shows the electrode of the flat panel display and the connecting portion of the display side. A step of interposing a strip-shaped anisotropic conductive film between the display-side terminals and (b) shows a step of thermocompression-bonding them.

[Explanation of symbols]

1 Flexible Wiring Circuit Board for Flat Panel Display 2 Base Insulation Layer 3 Conductor Layer 5 Wiring Pattern 9 Display Side Connection 10 Display Side Terminal 12 Reinforcing Metal Foil 21 Flat Panel Display 22 Electrode

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Claims (3)

[Claims] 1. A plurality of electrodes and a plurality of the wiring patterns formed on a flat panel display, comprising: a base insulating layer; and a conductor layer formed on the surface of the base insulating layer and including a plurality of wiring patterns. A flexible printed circuit board for a flat panel display in which a connecting portion for connecting each is formed, wherein the connecting portion corresponds to a plurality of the wiring patterns,
A plurality of terminal portions for connecting to each of the plurality of electrodes are provided in line at a predetermined pitch, and the plurality of terminal portions and the thickness direction are provided on the back surface of the insulating base layer in the connecting portion. 2. A flexible printed circuit board for flat panel displays, characterized in that a strip-shaped metal reinforcing layer is provided along the alignment direction of the terminal portions so as to overlap with each other. 2. A cover insulating layer covering the conductor layer is provided, the connecting portion is formed so that the conductor layer is exposed from the cover insulating layer, and the metal reinforcing layer is the cover insulating layer. The flexible printed circuit board for a flat panel display according to claim 1, wherein the flexible printed circuit board is provided so as to overlap with the thickness direction. 3. The connection portion is provided at an end portion of the flexible printed circuit board for a flat panel display, and the metal reinforcing layer is provided more inside than an end edge portion of the insulating base layer. The flexible printed circuit board for a flat panel display according to claim 1, wherein the flexible printed circuit board is provided.