JP2007250616A - Flexible circuit board, manufacturing method thereof, electro-optical apparatus, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible circuit board that can suppress reflection phenomenon of signal through matching of characteristic impedance of conductive patterns which are conductive in the vertical direction, and also to provide a manufacturing method of such flexible circuit board, an electro-optical apparatus, and electronic device. <P>SOLUTION: The flexible circuit board is provided with a first conductive pattern on one surface of a flexible substrate, and a second conductive pattern on the other surface, in which the first conductive pattern and the second conductive pattern are electrically connected via through-holes provided to the substrates. In this flexible circuit board, an end in the through-hole side of the first conductive pattern and an end in the through-hole side of the second conductive pattern are crossing in the angle larger than 90° but smaller than 270° at the center of the through-holes. In the through-holes, an angle formed by an end part of the through-hole side of the first conductive pattern and the through-hole is larger than 90° when the substrates are viewed from the direction orthogonal to the substrate surface. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flexible circuit board, a method for manufacturing a flexible circuit board, an electro-optical device, and an electronic apparatus. In particular, the present invention relates to a flexible substrate provided with through-hole portions for electrically connecting conductive patterns on both sides of the substrate, a method for manufacturing such a flexible circuit substrate, an electro-optical device including such a flexible circuit substrate, and an electronic apparatus.

Conventionally, as one aspect of an electro-optical device, a pair of substrates each having an electrode formed thereon are arranged to face each other, and a voltage applied to a plurality of pixels that are intersecting regions of the electrodes is selectively turned on and off. A liquid crystal device that modulates light passing through a liquid crystal material of the pixel and displays an image such as an image or a character is often used.
In such a liquid crystal device, for the purpose of miniaturization and weight reduction, a flexible circuit board (FPC) is used in which a conductive pattern is formed on the surface of a flexible substrate and electronic components such as semiconductor elements and connectors are mounted. ing.

In this FPC, in order to improve the degree of freedom of arrangement of electronic components to be mounted, or in order to improve the degree of freedom of wiring of the conductive pattern, a conductive pattern is formed on both sides of a flexible substrate, It has been practiced to electrically connect the conductive patterns on both sides through through-hole portions provided in a flexible substrate.
As such an FPC, for example, an FPC manufacturing method capable of mounting components at high density is disclosed. More specifically, as shown in FIG. 16, after drilling a flexible substrate 401 having a metal foil on both sides, a step of applying metal plating 403, laminating a photosensitive resin film, and exposing and developing in the through hole portion The step of filling the photosensitive resin 404, the step of roughening the surface of the photosensitive resin and applying the metal plating 403 ', the formation of the etching resist pattern, the unnecessary metal foil is removed by etching, and then the etching resist is removed. It is a manufacturing method of flexible printed wiring consisting of a process (refer to patent documents 1).
JP-A-6-120640 (FIGS. 1 to 3)

However, as described in Patent Document 1, in a general FPC, a through-hole portion provided in a flexible substrate is formed in a direction perpendicular to the substrate surface. For this reason, the conductive member of the through hole portion is bent perpendicularly with respect to the conductive pattern on the substrate surface corresponding to the shape of the through hole portion, so that there is a problem that it is difficult to match the characteristic impedance. there were. Therefore, a signal reflection phenomenon occurs in the through-hole portion, and there is a risk that the liquid crystal device connected to the FPC may malfunction or display quality may be degraded.
In particular, in recent years, in electronic devices, the amount of drive signals has increased along with the higher definition of display panels, and the signal transmission speed has been increased. The influence of the reflection phenomenon is increasing.

Accordingly, the inventors of the present invention have made diligent efforts to incline the through-hole portion of the flexible circuit board so that the angle formed between the end portion of the conductive pattern and the through-hole portion exceeds 90 °. The inventors have found that the problem can be solved and completed the present invention.
That is, an object of the present invention is to provide a flexible circuit board capable of matching the characteristic impedance of a conductive pattern vertically conductive in the flexible circuit board and suppressing the signal reflection phenomenon. Another object of the present invention is to provide a method for manufacturing such a flexible circuit board, and an electro-optical device and an electronic apparatus provided with such a flexible circuit board.

According to the present invention, a through hole portion provided in a substrate, comprising a first conductive pattern formed on one surface of a flexible substrate and a second conductive pattern formed on the other surface. A flexible circuit board in which the first conductive pattern and the second conductive pattern are electrically connected via the first conductive pattern, the through-hole side end of the first conductive pattern and the second conductive pattern through The end on the hole side intersects with the through hole portion so as to form an angle larger than 90 ° and smaller than 270 °, and the through hole portion is viewed from the direction perpendicular to the substrate surface. A flexible circuit board characterized in that the angle formed between the end portion of the first conductive pattern on the through-hole portion side and the through-hole portion exceeds 90 ° is provided, and is described above. Solve the problem Rukoto can.
That is, the conductive pattern formed on both sides of the substrate is formed to intersect at an angle within a predetermined range, and the through-hole portion formed obliquely at a predetermined angle with respect to the substrate surface By electrically connecting the conductive patterns on both sides, it is possible to match the characteristic impedance in the through-hole portion and reduce the reflection of signals transmitted through the conductive pattern. Therefore, it is possible to reduce the malfunction of the electro-optical device or the like to which the flexible circuit board is connected and the deterioration of the display quality.

Further, in configuring the flexible circuit board of the present invention, it is preferable that the through-hole portion has a tapered shape having different opening areas on both sides.
With this configuration, it is easy to adjust the resistance value and area of the conductive member inside the through hole, and the characteristic impedance in the through hole portion can be easily matched.

Further, in configuring the flexible circuit board of the present invention, it is preferable to include a non-existing region of the conductive member in a part of the through hole portion.
By comprising in this way, the characteristic impedance of the electrically-conductive member in a through-hole part can be adjusted and it can be made easy to match.

Further, in configuring the flexible circuit board of the present invention, it is preferable that the angle formed between the end portion on the through hole portion side of the first conductive pattern and the through hole portion is set to a value within a range of 120 to 150 °.
With this configuration, it is possible to easily match the characteristic impedance while preventing the area of the region where the through-hole portion is formed from becoming excessively large.

In configuring the flexible circuit board of the present invention, the first conductive pattern and the second conductive pattern are made of the first conductive film, and the through-hole portion has a second resistance value higher than that of the first conductive film. It is preferable that it consists of a conductive film.
With this configuration, the resistance values of the conductive pattern formed on the substrate surface and the conductive member formed in the through hole portion can be easily matched, and the characteristic impedance can be easily matched.

In configuring the flexible circuit board of the present invention, it is preferable that the same film as the second conductive film is laminated on the first conductive film in the first conductive pattern and the second conductive pattern. .
By configuring in this way, it is possible to prevent the width and height of the first conductive pattern from becoming significantly large.

Another embodiment of the present invention includes a first conductive pattern formed on one surface of a flexible substrate and a second conductive pattern formed on the other surface, and is provided on the substrate. A method of manufacturing a flexible circuit board in which the first conductive pattern and the second conductive pattern are electrically connected via the through-hole portion,
Forming a first conductive pattern on one surface of the substrate;
The through hole side that intersects the other surface of the substrate so as to form an angle larger than 90 ° and smaller than 270 ° with the end portion on the through hole portion side of the first conductive pattern when the substrate is viewed in plan Forming a second conductive pattern having an end of
A through-hole portion that contacts at least a part of the first conductive pattern on one surface and contacts at least a part of the second conductive pattern on the other surface with respect to the substrate is orthogonal to the substrate surface. A step of forming the first conductive pattern so as to be inclined so that an angle formed between the end portion on the through hole portion side of the first conductive pattern and the through hole portion exceeds 90 °, and
Electrically connecting the first conductive pattern and the second conductive pattern by disposing a conductive member in the through hole portion; and
The manufacturing method of the flexible circuit board characterized by including.
That is, the first conductive pattern and the second conductive pattern formed on both surfaces of the substrate are formed to intersect at an angle within a predetermined range, and the first conductive pattern and the second conductive pattern are connected. By forming the through-hole portion in an oblique direction with a predetermined angle with respect to the substrate surface, a flexible circuit board that matches the characteristic impedance can be manufactured efficiently and easily.

Moreover, when implementing the manufacturing method of the flexible circuit board of this invention, it is preferable to form a through-hole part by making a drill or a laser penetrate from a diagonal direction with respect to a substrate surface.
By implementing in this way, the through-hole part which inclines with respect to a substrate surface can be formed easily.

Moreover, when implementing the manufacturing method of the flexible circuit board of this invention, it is preferable to form a through-hole part in the taper shape from which the opening area in both surfaces differs.
By carrying out in this way, it becomes easy to adjust the resistance value and area of the conductive member in the through hole portion, and the characteristic impedance can be easily matched.

According to still another aspect of the present invention, there is provided an electro-optical device in which a flexible circuit board is electrically connected to an electro-optical panel, and the flexible circuit board is provided on one surface of the flexible substrate. A first conductive pattern formed and a second conductive pattern formed on the other surface, and the first conductive pattern and the second conductive pattern are electrically connected via a through-hole portion provided in the substrate. When the substrate is viewed in plan, the end portion on the through hole portion side of the first conductive pattern and the end portion on the through hole portion side of the second conductive pattern are centered on the through hole portion. Intersecting to form an angle larger than 90 ° and smaller than 270 °, and the through-hole portion side of the first conductive pattern when viewed from the direction orthogonal to the substrate surface End and The electro-optical device is characterized in that the angle formed with the through-hole portion is inclined so as to exceed 90 °.
That is, by matching the characteristic impedance of the conductive pattern that is vertically conductive on the flexible circuit board, a reduction in signal reflection is suppressed, and an electro-optical device with excellent reliability that has few malfunctions and display defects. Can be provided.

Yet another embodiment of the present invention is an electronic apparatus including the above-described electro-optical device.
In other words, it is equipped with an electro-optical device that matches the characteristic impedance at a predetermined location and has few operation failures and display failures and is excellent in reliability. Therefore, it is easy to add various functions and provide highly reliable electronic equipment. Can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Embodiments relating to a flexible circuit board, a method for manufacturing a flexible circuit board, an electro-optical device, and an electronic apparatus according to the invention will be specifically described below with reference to the drawings. However, this embodiment shows one aspect of the present invention and does not limit the present invention, and can be arbitrarily changed within the scope of the present invention.
In addition, in each figure, what attached | subjected the same code | symbol has shown the same member, and may abbreviate | omit description suitably.

[First Embodiment]
The first embodiment of the present invention includes a first conductive pattern formed on one surface of a flexible substrate and a second conductive pattern formed on the other surface, and is provided on the substrate. This is a flexible circuit board in which a first conductive pattern and a second conductive pattern are electrically connected via a through-hole portion.
In the flexible circuit board according to the present embodiment, when the substrate is viewed in plan, the end portion on the through hole portion side of the first conductive pattern and the end portion on the through hole portion side of the second conductive pattern are the through hole portion. And the through-hole portion has a through-hole of the first conductive pattern when the substrate is viewed from a direction orthogonal to the substrate surface. It is characterized in that the angle formed by the end portion on the part side and the through-hole portion is inclined so as to exceed 90 °.

1. Overall Configuration FIG. 1 shows a flexible circuit board according to this embodiment. FIG. 1A is a plan view of the flexible circuit board 11, and FIG. 1B is a cross-sectional view of the XX cross section of FIG.
The flexible circuit board 11 includes a first conductive pattern 13 on one surface (upper side of FIG. 1B) of a flexible substrate 12 as a base, and the lower surface of FIG. 1B. The second conductive pattern 15 is provided on the side). The first conductive pattern 13 and the second conductive pattern 15 are electrically connected via a through hole portion 17 provided in the flexible substrate 12. Further, on each surface, protective films 19a and 19b are attached to the entire surface of the flexible substrate 12 on which the first and second conductive patterns 13 and 15 are formed using an adhesive material (not shown). Has been.

2. Flexible substrate The flexible substrate as the base of the flexible circuit substrate is a substrate made of, for example, polyimide resin or polycarbonate resin and having a thickness of about 15 to 50 μm. Such a flexible substrate can be bent as necessary when incorporated in an electro-optical device or an electronic apparatus, and the bending stress can be kept small. Accordingly, it is possible to reduce the size of the electro-optical device and the electronic device to which the flexible circuit board is connected.

3. Conductive pattern The first conductive pattern and the second conductive pattern formed on both surfaces of the flexible substrate constitute an electrical wiring made of a conductive material, for example, an electro-optic to which the flexible circuit substrate is connected. A signal for driving the device is transmitted. In particular, as the signal transmission speed increases, the signal reflection phenomenon due to the mismatch of the characteristic impedance of the conductive pattern appears more prominently, and the display quality is likely to deteriorate. A conductive pattern as a high-speed transmission path is preferable.

  Among the conductive patterns shown in FIG. 1A, the first conductive pattern 13 has one end extended to the end of the flexible substrate 12 to form a terminal 14, and the end portion is placed on a glass substrate or the like. It is electrically connected to the provided terminal. The other end of the first conductive pattern 13 extends to the through hole portion 17. On the other hand, one end of the second conductive pattern 15 is electrically connected to a connector portion 16 mounted on the flexible substrate 12, and the connector portion 16 is connected to an electronic component (not shown). Further, the other end of the second conductive pattern 15 is extended to the through-hole portion 17 like the first conductive pattern 13.

Further, as illustrated in FIG. 1A, the first conductive pattern 13 and the second conductive pattern 15 are formed on the through hole portion 17 side of the first conductive pattern 13 when the substrate 12 is viewed in plan view. The end portion 13 </ b> A and the end portion 15 </ b> A on the through hole portion 17 side of the second conductive pattern 15 intersect with each other so as to form an angle larger than 90 ° and smaller than 270 ° with the through hole portion 17 as the center.
Since the end portion 13A of the first conductive pattern 13 and the end portion 15A of the second conductive pattern 15 intersect in this way, the first conductive pattern 13 is formed in an oblique direction with an angle within a predetermined range with respect to the substrate surface. Through the through-hole portion 17, it is possible to match the characteristic impedance on both the outlet side and the inlet side of the through-hole portion 17.

For example, in the first conductive pattern 13 and the second conductive pattern 15 shown in FIG. 1A, when the substrate 12 is viewed in plan, the respective end portions 13A and 15A on the through hole portion 17 side are 180 °. It is formed so as to form an angle, that is, linearly. In addition to this, as shown in FIG. 2, when the substrate is viewed in plan, the end portion 13 </ b> A of the first conductive pattern and the end portion 15 </ b> A of the second conductive pattern are 90 around the through-hole portion 17. It suffices if they intersect so as to form an angle that is larger than ° and smaller than 270 °.
That is, when the end portion of the first conductive pattern and the end portion of the second conductive pattern form an angle within the range of 0 to 90 ° or 270 to 360 ° with the through hole portion as the center, This is because the angle formed between the end portion of any one of the conductive patterns and the through-hole portion is a value of 90 ° or less, and the characteristic impedance tends to be discontinuous.

Here, it is preferable that the first and second conductive patterns are made of a first conductive film, and the through-hole portion is made of a second conductive film having a resistance value higher than that of the first conductive film. This is because the conductive member in the through-hole portion is formed using the second conductive film having a relatively high resistance value while adjusting the width and thickness, so that the conductive pattern on the substrate and the through-hole portion are formed. This is because it is possible to easily match the characteristic impedance with the conductive member.
Further, as shown in FIG. 3, the first and second conductive patterns are formed on the first conductive patterns 13 a and 15 a constituting the first conductive pattern 13 and the second conductive pattern 15. It is preferable that the same films 13b and 15b as the second conductive film 22 constituting the above are laminated. This is to prevent the width and height of the first conductive pattern 13 from becoming excessively large and restricting the wiring design of the wiring pattern.

As shown in FIG. 3, when the conductive patterns 13 and 15 have a laminated structure, the second conductive films 13b and 15b are preferably made of a corrosion resistant material. The reason for this is to prevent the resistance value from being increased due to oxidation of the conductive pattern and the like, resulting in a decrease in signal transmission speed and a mismatch in characteristic impedance.
As the first and second conductive patterns having such a laminated structure, for example, a laminated structure in which a second conductive film made of a nickel-gold alloy is laminated on a first conductive film mainly composed of copper. be able to.

In addition, while keeping the resistance value as low as possible, the thickness of the entire flexible circuit board is not excessively increased, and the conductive pattern is not disconnected when the flexible circuit board is bent. For example, the thickness of each of the two conductive films is preferably set to a value in the range of 10 to 30 μm.
In addition, the width of the first and second conductive patterns is set so that the flexible circuit board does not become excessively large and the degree of freedom in routing the conductive pattern is not limited while keeping the resistance value as low as possible. For example, it is preferable to set the value within a range of 30 to 60 μm.
Further, the width of the entire conductive pattern around the through hole portion is appropriately selected according to the size of the opening of the through hole portion. For example, when the through hole portion is formed by a drill, the width is 250 to 350 μm. A value within the range can be set, and when the through-hole portion is formed by a laser, a value within the range of 150 to 250 μm can be set.

4). Through-hole part A through-hole part is a site | part for electrically conducting the 1st conductive pattern and 2nd conductive pattern which were formed in both surfaces of the flexible substrate. As shown in FIG. 1B, the flexible circuit board according to the present invention has the first conductive pattern 13 when the through-hole portion 17 is viewed from the direction orthogonal to the board surface 12A. The angle θ formed by the end portion 13A on the through-hole portion 17 side and the through-hole portion 17 is inclined so as to exceed 90 °.
That is, according to the flexible circuit board 11 of the present invention, the conductive member 22 that conducts the first conductive pattern 13 and the second conductive pattern 15 in the through-hole portion 17 is perpendicular to the conductive patterns 13 and 15. It is no longer bent in the direction or less than 90 °, and the characteristic impedance can be easily matched. Therefore, the reflected signal is less likely to be reflected, and the occurrence of malfunctions can be reduced and the display quality can be improved.

More specifically, when the angle θ formed between the end portion on the through hole portion side of the first conductive pattern and the through hole portion is formed perpendicularly, as shown in FIG. It is known that the conductive member (metal plating) 403 is bent vertically, and the length of the signal transmission path is partially different, so that characteristic impedance mismatch is likely to occur. Further, even when the angle θ formed between the end portion on the through hole portion side of the first conductive pattern and the through hole portion is less than 90 °, the signal is further increased than when the angle θ is formed vertically. Since the lengths of the transmission paths are partially different, characteristic impedance mismatches are likely to occur.
On the other hand, when the substrate is viewed from the direction orthogonal to the substrate surface as in the present invention, the angle θ formed between the end portion on the through hole portion side of the first conductive pattern and the through hole portion is 90. In the case where it is formed to be inclined so as to exceed 60 °, the length of the signal transmission path passing through the upper layer side and the lower layer side of the conductive pattern can be made close, so that the characteristic impedance can be easily matched. Further, the end portions on the through hole portion side in each of the first conductive pattern and the second conductive pattern intersect with each other at an angle larger than 90 ° and smaller than 270 ° around the through hole portion. Since the angle formed by the end portion of the conductive pattern 2 and the through hole portion is also formed to exceed 90 °, matching of the characteristic impedance as a whole can be achieved.

Further, when forming the through-hole portion inclined with respect to the substrate surface, the end portion 13A on the through-hole portion 17 side of the first conductive pattern 13 and the through-hole portion 17 shown in FIG. The angle formed is preferably set to a value within the range of 120 to 150 °.
This is because if the tilt angle is less than 120 °, the characteristic impedance may not be sufficiently matched. On the other hand, if the inclination angle exceeds 150 °, the area of the through-hole formation region becomes large, which may affect the pattern design of the conductive pattern and eventually increase the size of the flexible circuit board. is there.
Therefore, the inclination angle of the through hole portion with respect to the substrate surface is more preferably set to a value within the range of 125 to 145 °, and further preferably set to a value within the range of 130 to 140 °.

As shown in FIG. 4, when the through-hole portion formed in an oblique direction with a predetermined angle with respect to the substrate surface is provided, the through-hole portion has a tapered through-hole having different opening areas on both sides as shown in FIG. The portion 17 ′ is preferable.
This is because the inner area of the through-hole portion can be increased if it is a tapered through-hole portion, and the resistance value can be adjusted by changing the area of the conductive member formed in the through-hole portion. is there. Also, when placing the conductive member inside the through hole portion, when performing the plating process, it is easy to place the base material in the through hole, so that the adhesion of the conductive member inside the through hole is increased, This is because the reliability against peeling and the like can be improved.

Further, as another example of the tapered through hole portion, as shown in FIG. 5, the opening area is widened from the inside of the through hole portion toward the opening portions on both sides of the flexible substrate. The through-hole portion 17 ″ is also preferable.
This is because the inclination angle of the edge portion of the through hole portion with respect to the substrate surface can be made relatively gentle on both sides of the inlet and the outlet of the through hole portion. Therefore, it is possible to more easily match the characteristic impedance between the conductive pattern and the conductive member.
In addition, the inclination angle with respect to the substrate surface when the through-hole portion is tapered means a linear inclination angle connecting the centers of the openings on both sides of the flexible substrate.

Further, the planar shape of the through hole portion is not particularly limited, and a circular shape, an elliptical shape, a rectangular shape, or the like can be appropriately selected. However, when the through-hole portion is formed using a drill-like object or a laser, the circular through-hole portion can be easily formed.
In addition, the diameter of the through hole portion is configured to correspond to the member that forms the opening portion with respect to the flexible substrate. For example, when the opening portion is formed using a drill-like material, The diameter of the hole portion can be set to a value within the range of 150 to 200 μm.
On the other hand, when the opening portion of the flexible substrate is formed using a laser, the diameter of the through hole portion is relatively small and can be set to a value in the range of 100 to 150 μm.
The wiring design of the conductive pattern on the flexible substrate can be performed relatively easily by reducing the diameter of the through-hole portion as in the case where the opening is formed in the flexible substrate using a laser. .

The conductive member formed in the through hole portion is preferably made of a material having higher resistance characteristics than the conductive pattern formed on the substrate surface.
This is because even if the area per unit length of the conductive member in the through hole portion is small, matching of the characteristic impedance between the conductive pattern and the conductive member of the through hole portion can be achieved.
For example, as described above, when the first and second conductive patterns have a stacked structure in which a second conductive film made of a nickel-gold alloy is stacked on a first conductive film containing copper as a main component. The conductive member of the through hole portion is formed using only a conductive film made of a nickel-gold alloy, whereby the resistance characteristic per unit length can be made larger than that of the conductive pattern. If the width and area are controlled, the resistance value of the conductive member in the through-hole portion can be prohibited from the resistance value of the conductive pattern. This makes it possible to match the characteristic impedance between the conductive pattern and the conductive member in the through-hole portion.

Further, as shown in FIGS. 6A to 6B, it is preferable that a part of the through hole portion 17 includes a non-existing region 22 a of the conductive member 22.
This is because the resistance value per unit length of the conductive member can be approximated to the resistance value per unit length of the conductive pattern by adjusting the area of the conductive member existing in the through hole portion. . Therefore, the characteristic impedance in the through hole portion can be further improved.
Here, the through-hole portion 17 shown in FIGS. 6A to 6B is a through-hole portion 17 in which the conductive member 22 is formed only on a part of the inner peripheral surface inside the through-hole portion 17. Specifically, FIG. 6A is an example in which the conductive member 22 is formed in a half region of the inner peripheral surface of the through-hole portion 17 and the remaining half region is a non-existing region 22a. FIG. 6B shows an example in which the inner peripheral surface of the through-hole portion 17 is formed in a stripe shape with the presence region and the non-existence region 22a of the conductive member 22.

Further, in the case where the conductive member non-existing region is provided in a part of the through hole portion, as shown in FIG. 7A or 7B, at least one of the inlet and the outlet of the through hole portion 17 is flexible. It is also preferable to provide the non-existence region 24 of the conductive patterns 13 and 15 in a part of the periphery of the openings 12a and 12b of the conductive substrate 12.
The reason for this is to match the characteristic impedance not only in the through-hole portion but also in the inlet and outlet portions of the through-hole portion.

5). Protective film As shown in FIG. 1B, the flexible circuit board 11 of the present embodiment has a structure in which the first and second conductive patterns 13 and 15 are formed on both surfaces of the flexible board 12. Further, protective films 19a and 19b are attached. The protective films 19a and 19b are sheet-like members made of an insulating material mainly composed of an acrylic resin, an epoxy resin, or the like, and are attached using an adhesive material (not shown).
By providing such a protective film, it is possible to cover the conductive pattern other than the connection portion such as the connection portion with the glass substrate or the electronic component to ensure insulation, and to prevent the conductive pattern from being eroded or damaged.
As such a protective film, for example, a laminate in which an adhesive material layer having a thickness of about 15 to 20 μm is laminated on one surface of an insulating sheet having a thickness of about 10 to 15 μm can be used.

[Second Embodiment]
A second embodiment of the present invention includes a first conductive pattern formed on one surface of a flexible substrate and a second conductive pattern formed on the other surface, and is provided on the substrate. This is a method of manufacturing a flexible circuit board in which a first conductive pattern and a second conductive pattern are electrically connected via a through-hole portion.
Such a method of manufacturing a flexible circuit board includes a step of forming a first conductive pattern on one surface of the board;
The through hole side that intersects the other surface of the substrate so as to form an angle larger than 90 ° and smaller than 270 ° with the end portion on the through hole portion side of the first conductive pattern when the substrate is viewed in plan Forming a second conductive pattern having an end of
A through-hole portion that contacts at least a part of the first conductive pattern on one surface and contacts at least a part of the second conductive pattern on the other surface with respect to the substrate is orthogonal to the substrate surface. A step of forming the first conductive pattern so as to be inclined so that an angle formed between the end portion on the through hole portion side of the first conductive pattern and the through hole portion exceeds 90 °, and
A step of electrically connecting the first conductive pattern and the second conductive pattern by disposing a conductive member in the through hole portion.
Hereinafter, as a method for manufacturing a flexible circuit board according to this embodiment, the method for manufacturing a flexible circuit board described in the first embodiment shown in FIG. 1 will be described as an example.

1. Formation of conductive pattern First, an insulating flexible substrate made of polyimide resin or the like having a thickness of about 10 to 30 μm is prepared, the first conductive pattern is formed on one surface, and the other surface is formed. A second conductive pattern is formed.
The method for forming these conductive patterns is not particularly limited. When the conductive pattern is configured as a stacked structure of a first conductive film mainly composed of copper and a second conductive film made of a nickel-gold alloy, for example, as shown in FIG. After laminating a first conductive layer 13a ′ containing copper as a main component on the flexible substrate 12 by sputtering or the like, plating 13b ′ using a nickel-gold alloy is performed. Next, patterning is performed into a predetermined shape by a photolithography method, an etching method, or the like to form a first conductive pattern made up of the first conductive film 13a and the second conductive film 13b as shown in FIG. 8B. . Next, as shown in FIGS. 8C to 8D, a second conductive pattern having a laminated structure is formed on the other surface side of the flexible substrate by the same method.

  Here, when forming the first and second conductive patterns, when the substrate is viewed in plan, the end portion on the through hole portion side of the first conductive pattern and the through hole portion side of the second conductive pattern are formed. The end portions are formed so as to intersect with each other so as to form an angle larger than 90 ° and smaller than 270 ° around the position where the through-hole portion is formed.

In addition, regarding the width and height of the conductive pattern, considering the resistance value and the overall size, for example, the width of the first conductive pattern is set to a value in the range of 30 to 60 μm, and the height is set to 10 to 10 mm. The value is within a range of 30 μm.
Further, the width of the first conductive pattern is determined in consideration of the size of the opening of the through hole in the region where the through hole portion is formed. For example, the width of the first conductive pattern in the region is set to 250. It can be set to about 350 μm.
At this time, as shown in FIG. 9, the region where the through-hole portion is formed is formed in a part of the periphery of the portion to be the opening portions 12 a and 12 b of the through-hole portion 17 and the non-existing region 24 of the conductive patterns 13 and 15. It is preferable that the patterning is performed so as to form. This is because it is easy to achieve matching with the characteristic impedance of the conductive member in the through hole portion.
Even if formed in this way, as will be described later, since the through-hole portion of the flexible circuit board of the present invention is formed obliquely with a predetermined angle with respect to the substrate surface, the conductive member inside the through-hole portion is formed. Can be securely connected.

2. Formation of Through-Hole Portion Next, a through-hole portion that contacts at least part of the first conductive pattern on one side and at least part of the second conductive pattern on the other side with respect to the flexible substrate Is formed so that the angle formed between the end portion on the through hole portion side of the first conductive pattern and the through hole portion exceeds 90 ° when the substrate is viewed from a direction orthogonal to the substrate surface. To do.
Thus, by forming the through-hole portion obliquely with a predetermined angle with respect to the substrate surface, it is possible to match the characteristic impedance in the through-hole portion and suppress the reflection phenomenon of the transmitted signal.
The formation method of the through hole is not particularly limited. For example, as shown in FIGS. 10A and 10B, the laser 26 or the drill 28 is penetrated from the oblique direction with respect to the substrate surface 12A. By doing so, the through-hole portion 17 can be easily formed in an oblique direction with respect to the substrate surface 12A. In particular, by forming the through-hole portion 17 using the laser 26, the through-hole portion 17 having a relatively small diameter can be formed, and restrictions on the wiring design of the conductive pattern can be reduced.

Further, in forming the through hole portion, it is preferable to form the taper shape having different opening areas on the surface side on which the first conductive pattern is formed and on the surface side on which the second conductive pattern is formed.
This is because the area in the through hole portion can be increased, so that the conductive member can be easily formed inside the through hole portion, and the area of the conductive member to be formed can be easily controlled.

  For example, when forming a through hole part using the drill or laser mentioned above, as shown to FIG. 11 (a)-(b), in the state which penetrated the laser 26 grade | etc., To the board | substrate of the said laser 26, etc. By changing the angle, the tapered through-hole portion 17 ′ can be formed. Also, as shown in FIGS. 12A to 12B, the tapered through-hole portion 17 ′ can be formed also by making the traveling direction of the laser 26 etc. different and making it penetrate a plurality of times.

  Further, when the through-hole portion is tapered, the tapered through-hole portion 17 ″ as shown in FIG. 5 can be formed by varying the inlet and outlet positions and the inclination angle with respect to the substrate surface. .

3. Formation of Conductive Member Next, a conductive member is formed in the through hole portion, and the first conductive pattern and the second conductive pattern are electrically connected. For example, the conductive member can be disposed by performing a known plating process on the inside of the through hole portion.
At this time, it is preferable to form a non-existing region 22a of the conductive member 22 in a part of the through-hole part 17 as shown in FIGS. 6 and 7 by masking a part of the through-hole part. The reason for this is that by controlling the resistance value per unit length of the conductive member and approximating the resistance value per unit length of the conductive pattern, the characteristic impedance of the conductive pattern and the characteristic impedance of the through-hole portion are further increased. This is because they can be matched.

4). Formation of Protective Film Next, although not shown in the figure, a flexible circuit board as shown in FIG. 3 is obtained by applying a protective film to each surface side of the flexible substrate on which the first and second conductive patterns are formed. 11 is formed.
The formation of the protective film can be appropriately performed using a known method. For example, an adhesive material layer having a thickness of about 15 to 20 μm is formed on one surface of an insulating sheet having a thickness of about 10 to 15 μm. This is done by sticking the laminated layers to a flexible substrate on which a conductive pattern is formed.

5). Next, the flexible circuit board of the present embodiment is mounted by mounting electronic components such as connectors and semiconductor elements on the terminal portions of the first conductive pattern or the second conductive pattern (not shown). Can be manufactured.

[Third Embodiment]
The third embodiment of the present invention is an electro-optical device in which the flexible circuit board described in the first embodiment is electrically connected to an electro-optical panel.
In this embodiment, a liquid crystal device using a liquid crystal panel including a TFT element (Thin Film Transistor) as an electro-optical panel will be described. However, in addition to this, it is applicable to various electro-optical devices to which a flexible circuit board is electrically connected, such as a liquid crystal device using a liquid crystal panel provided with a TFD element (Thin Film Diode), an electroluminescence device, and the like. Can do.

  In the following description, a liquid crystal panel refers to a state in which a liquid crystal material is injected between a pair of substrates bonded with a sealing material, and a flexible circuit board, an electronic component, a light source, and the like are included in the liquid crystal panel. The attached state is referred to as a liquid crystal device.

FIG. 13 is a schematic perspective view of the liquid crystal device 10 of the present embodiment, and FIG. 14 is a cross-sectional view of a pixel region portion of the liquid crystal panel 20 used in the liquid crystal device 10.
As shown in FIG. 13, in the liquid crystal device 10, the counter substrate 30 and the element substrate 60 are bonded to each other at the peripheral portion by the sealing material 23, and are surrounded by the counter substrate 30, the element substrate 60 and the sealing material 23. A liquid crystal material (not shown) is sealed in the gap.
In the liquid crystal panel 20 provided in the liquid crystal device 10, the element substrate 60 has a substrate extending portion 60 </ b> T that extends outward from the outer shape of the counter substrate 30. In addition, an external connection terminal 67 is formed on the surface of the substrate extension 60 </ b> T that holds a liquid crystal material (not shown), and the semiconductor element 91 is connected to the external connection terminal 67. A panel driving flexible circuit board (FPC) 11 is connected.

Further, as shown in FIG. 14, the counter substrate 30 is formed of glass, plastic, or the like. On the counter substrate 30, a color filter, that is, colored layers 37r, 37g, and 37b, and the colored layers 37r, 37g, and 37b are formed. The counter electrode 33 is formed on the counter electrode 33, and the alignment film 45 is formed on the counter electrode 33. In addition, an insulating layer 41 for optimizing retardation is provided between the colored layers 37r, 37g, and 37b and the counter electrode 33 in the reflective region R.
Here, the counter electrode 33 is a planar electrode formed over the entire surface of the counter substrate 30 with ITO (indium tin oxide) or the like. In addition, the colored layers 37r, 37g, and 37b are disposed at positions facing the pixel electrode 63 on the element substrate 60 side, such as R (red), G (green), B (blue), or C (cyan), M (magenta), and Y. A color filter element of any color such as (yellow) is provided. A black mask or black matrix, that is, a light shielding film 39 is provided next to the colored layers 37 r, 37 g, and 37 b and at a position that does not face the pixel electrode 63.

The element substrate 60 facing the counter substrate 30 is formed of glass, plastic, or the like. On the element substrate 60, a TFT element 69 as an active element functioning as a switching element and a transparent insulating film 81 are sandwiched. And the pixel electrode 63 formed in the upper layer of the TFT element 69.
Here, the pixel electrode 63 is formed as a light reflection film 79 (63a) for performing reflective display in the reflective region R, and is formed as a transparent electrode 63b with ITO or the like in the transmissive region T. . The light reflection film 79 as the pixel electrode 63a is formed of a light reflective material such as Al (aluminum) or Ag (silver). An alignment film 85 made of a polyimide-based polymer resin is formed on the pixel electrode 63, and a rubbing process as an alignment process is performed on the alignment film 85.

  Further, a phase difference plate 47 is formed on the outer surface (that is, the upper side in FIG. 14) of the counter substrate 30, and a polarizing plate 49 is further formed thereon. Similarly, a retardation plate 87 is formed on the outer surface of the element substrate 60 (that is, the lower side in FIG. 14), and a polarizing plate 89 is further formed thereunder. Further, a backlight unit (not shown) is disposed below the element substrate 60.

The TFT element 69 includes a gate electrode 71 formed on the element substrate 60, a gate insulating film 72 formed on the entire area of the element substrate 60 on the gate electrode 71, and the gate insulating film 72 interposed therebetween. A semiconductor layer 70 formed above the gate electrode 71, a source electrode 73 formed on one side of the semiconductor layer 70 via a contact electrode 77, and a contact electrode 77 on the other side of the semiconductor layer 70. And a drain electrode 66 formed through the electrode.
The gate electrode 71 extends from the gate bus wiring (not shown), and the source electrode 73 extends from the source bus wiring (not shown). Further, a plurality of gate bus lines extend in the horizontal direction of the element substrate 60 and are formed in parallel in the vertical direction at equal intervals, and the source bus lines cross the gate bus lines with the gate insulating film 72 interposed therebetween. A plurality of lines extending in the vertical direction are formed in parallel in the horizontal direction at equal intervals.
Such a gate bus wiring is connected to a liquid crystal driving IC (not shown) and functions as, for example, a scanning line, while a source bus wiring is connected to another driving IC (not shown), for example, a signal line. Acts as
The pixel electrode 63 is formed in a region excluding a portion corresponding to the TFT element 69 in a rectangular region defined by the gate bus wiring and the source bus wiring intersecting each other.

Here, the gate bus wiring and the gate electrode can be formed of chromium, tantalum, or the like, for example. The gate insulating film is formed of, for example, silicon nitride (SiN _x ), silicon oxide (SiO _x ), or the like. Further, the semiconductor layer can be formed of, for example, doped a-Si, polycrystalline silicon, CdSe, or the like. Further, the contact electrode can be formed of, for example, a-Si, and the source electrode and the source bus wiring and the drain electrode integrated therewith can be formed of, for example, titanium, molybdenum, aluminum, or the like.

The organic insulating film 81 is formed over the entire area of the element substrate 60 so as to cover the gate bus lines, the source bus lines, and the TFT elements. However, a contact hole 83 is formed in a portion corresponding to the drain electrode 66 of the organic insulating film 81, and the pixel electrode 63 and the drain electrode 66 of the TFT element 69 are electrically connected at the contact hole 83.
In addition, in the organic insulating film 81, a resin film having a concavo-convex pattern composed of a regular or irregular repetitive pattern of peaks and valleys is formed as a scattering shape in a region corresponding to the reflective region R. Has been. As a result, the light reflection film 79 (63a) laminated on the organic insulating film 81 also has a light reflection pattern composed of an uneven pattern. However, this uneven pattern is not formed in the transmission region T.

  As shown in FIG. 13, in the liquid crystal device 10 of the present embodiment, the flexible circuit board 11 is electrically connected to the substrate overhanging portion of the element substrate constituting the liquid crystal panel. The flexible circuit board 11 includes conductive patterns on both sides of a flexible substrate, and the conductive patterns on both sides are electrically connected via through-hole portions provided on the substrate. It is formed in an oblique direction with a predetermined angle with respect to the surface. The details of the configuration of the flexible circuit board can be the same as those already described in the first embodiment, and thus the description thereof is omitted here.

In the liquid crystal device 10 including the liquid crystal panel 20 having the above-described structure, during reflective display, external light such as sunlight or indoor illumination light enters the liquid crystal device 10 from the counter substrate 30 side, The light passes through the colored layers 37r, 37g, 37b and the liquid crystal material 21 to reach the light reflecting film 79, is reflected there, and passes again through the liquid crystal material 21, the colored layers 37r, 37g, 37b, etc. Reflection display is performed by exiting to.
On the other hand, in the transmissive display, the illumination device 11 is turned on, and the light emitted from the illumination device 11 passes through the transparent electrode 63b portion, and the colored layers 37r, 37g, 37b, and the liquid crystal material 21. , And the like, and is transmitted to the outside of the liquid crystal device 10, whereby transmissive display is performed.

  Since the through-hole portion in the flexible circuit board is formed to be inclined at a predetermined angle with respect to the end portion of the conductive pattern formed on the substrate, the transmission amount of the driving signal of the liquid crystal panel can be reduced. In many cases, even when the transmission speed is increased, the characteristic impedance is matched in the through-hole portion, and the signal reflection phenomenon is less likely to occur. Therefore, it is possible to reduce the malfunction of the liquid crystal panel and the deterioration of the display quality, and to obtain a liquid crystal device having excellent display quality and excellent long-term reliability.

[Fourth Embodiment]
The fourth embodiment of the present invention is an electronic apparatus including the electro-optical device according to the third embodiment.
FIG. 15 is a schematic configuration diagram showing the overall configuration of the electronic apparatus of the present embodiment. The electronic apparatus includes a liquid crystal panel 20 provided in the liquid crystal device and a control unit 200 for controlling the liquid crystal panel 20. In FIG. 15, the liquid crystal panel 20 is conceptually divided into a panel structure 20 </ b> A and a drive circuit 20 </ b> B composed of a semiconductor element (IC) or the like. The control means 200 also includes a display information output source 201, a display processing circuit 202, a power supply circuit 203, and a timing generator 204.
The display information output source 201 includes a memory composed of a ROM (Read Only Memory), a RAM (Random Access Memory), etc., a storage unit composed of a magnetic recording disk, an optical recording disk, etc., and a tuning that outputs a digital image signal in a synchronized manner. And is configured to supply display information to the display processing circuit 202 in the form of an image signal having a predetermined format based on various clock signals generated by the timing generator 204.

The display processing circuit 202 includes various well-known circuits such as a serial-parallel conversion circuit, an amplification / inversion circuit, a rotation circuit, a gamma correction circuit, and a clamp circuit, and executes processing of input display information to display the image. Information is supplied together with the clock signal CLK to the drive circuit 20B. Furthermore, the drive circuit 20B can include a first electrode drive circuit, a second electrode drive circuit, and an inspection circuit. Further, the power supply circuit 203 has a function of supplying a predetermined voltage to each of the above-described components.
And if it is the electronic device of this embodiment, the liquid crystal using the flexible circuit board formed so that a through-hole part may incline so that a predetermined angle may be made with respect to the edge part of the conductive pattern formed on the board | substrate. Since the device is provided, it is possible to provide an electronic device with few malfunctions and excellent display quality.

  According to the present invention, since the through-hole portion is formed so as to be inclined at a predetermined angle with respect to the end portion of the conductive pattern formed on the substrate, the flexible circuit board in which the characteristic impedance is matched Can be provided. Therefore, an electro-optical device such as a liquid crystal device provided with a TFT element and an electronic device, such as a mobile phone or a personal computer, and a liquid crystal television and a viewfinder type configured by electrically connecting flexible circuit boards.・ Monitor direct-view video tape recorder, car navigation device, pager, electrophoresis device, electronic notebook, calculator, word processor, workstation, videophone, POS terminal, electronic device with touch panel, device with electron-emitting device ( It can be widely applied to FED: Field Emission Display and SCEED: Surface-Conduction Electron-Emitter Display.

It is the top view and sectional drawing of the flexible circuit board of 1st Embodiment. It is a figure which shows the state which a 1st conductive pattern and a 2nd conductive pattern cross | intersect. It is sectional drawing with which it uses in order to demonstrate the conductive pattern which consists of laminated structures. It is a figure provided in order to demonstrate a taper-shaped through-hole part. It is a figure provided in order to explain a through-hole part with tapered ends. It is a figure which shows the state which provided the non-existing area | region of the electrically-conductive member in a part of through-hole part. It is a figure which shows the state which provided the non-existing area | region of the conductive pattern in a part of opening part of a through-hole part. It is for demonstrating the formation process of the conductive pattern concerning 2nd Embodiment. It is a figure provided in order to demonstrate the formation location of a conductive pattern. It is a figure which shows an example of the formation method of a through-hole part. It is a figure provided in order to demonstrate the formation method of a taper-shaped through-hole part (the 1). It is a figure provided in order to demonstrate the formation method of a taper-shaped through-hole part (the 2). It is a schematic perspective view which shows the liquid crystal device of 3rd Embodiment. It is sectional drawing with which it uses in order to demonstrate the structure of a liquid crystal panel. It is a block diagram which shows schematic structure of the electronic device of 4th Embodiment. It is a figure for demonstrating the structure of the through-hole part of the conventional flexible circuit board.

Explanation of symbols

10: liquid crystal device (electro-optical device), 11: flexible circuit board, 12: flexible substrate, 12A: substrate surface, 12a: opening, 13: first conductive pattern, 13A: end of first conductive pattern Part, 14: terminal, 15: second conductive pattern, 15: end part of the second conductive pattern, 16: connector part, 17 · 17 ′ / 17 ″: through-hole part, 19a, 19b: protective film, 20: Liquid crystal panel, 22: Conductive member, 24: Non-existing region of conductive pattern, 26: Laser, 28: Drill, 30: Counter substrate (color filter substrate), 60: Element substrate, 60T: Substrate overhang

Claims (11)

A first conductive pattern formed on one surface of the flexible substrate and a second conductive pattern formed on the other surface, and the first conductive pattern formed on the substrate through a through-hole portion provided on the substrate. In the flexible circuit board in which the first conductive pattern and the second conductive pattern are electrically connected,
When the substrate is viewed in plan, the end portion on the through hole portion side of the first conductive pattern and the end portion on the through hole portion side of the second conductive pattern are centered on the through hole portion. Intersect to make an angle greater than 90 ° and less than 270 °,
In the through hole portion, when the substrate is viewed from a direction orthogonal to the substrate surface, an angle formed between an end portion on the through hole portion side of the first conductive pattern and the through hole portion is 90 °. A flexible circuit board characterized by being inclined so as to exceed.   The flexible circuit board according to claim 1, wherein the through-hole portion has a tapered shape with different opening areas on both sides.   The flexible circuit board according to claim 1, wherein a part of the through hole portion includes a non-existing region of a conductive member.   The angle formed by the end portion on the through hole portion side of the first conductive pattern and the through hole portion is set to a value within a range of 120 to 150 °. A flexible circuit board according to the item.   The first conductive pattern and the second conductive pattern are made of a first conductive film, and the through-hole portion is made of a second conductive film having a resistance value higher than that of the first conductive film. The flexible circuit board as described in any one of Claims 1-4.   6. The flexible circuit board according to claim 5, wherein the same film as the second conductive film is laminated on the first conductive film in the first conductive pattern and the second conductive pattern. . A first conductive pattern formed on one surface of the flexible substrate and a second conductive pattern formed on the other surface, and the first conductive pattern formed on the substrate through a through-hole portion provided on the substrate. In the manufacturing method of the flexible circuit board in which the first conductive pattern and the second conductive pattern are electrically connected,
Forming a first conductive pattern on one surface of the substrate;
When the substrate is viewed in plan, the other surface of the substrate intersects with the end of the first conductive pattern on the through hole portion side so as to form an angle greater than 90 ° and smaller than 270 °. Forming the second conductive pattern having an end on the through hole side;
A through-hole portion that contacts at least part of the first conductive pattern on the one surface and contacts at least part of the second conductive pattern on the other surface with respect to the substrate. A step of forming the first conductive pattern so as to be inclined so that an angle formed by the end portion on the through hole portion side of the first conductive pattern and the through hole portion exceeds 90 ° when viewed from a direction perpendicular to the surface. When,
Electrically connecting the first conductive pattern and the second conductive pattern by disposing a conductive member in the through hole portion;
A method for manufacturing a flexible circuit board, comprising:   The method for manufacturing a flexible circuit board according to claim 7, wherein the through-hole portion is formed by penetrating a drill or a laser from an oblique direction with respect to the substrate surface.   9. The method of manufacturing a flexible circuit board according to claim 7, wherein the through-hole portion is formed in a tapered shape having different opening areas on both surfaces. In an electro-optical device in which a flexible circuit board is electrically connected to an electro-optical panel,
The flexible circuit board includes a first conductive pattern formed on one surface of a flexible substrate and a second conductive pattern formed on the other surface, and a through hole provided in the substrate. The first conductive pattern and the second conductive pattern are electrically connected via a portion,
When the substrate is viewed in plan, the end portion on the through hole portion side of the first conductive pattern and the end portion on the through hole portion side of the second conductive pattern are centered on the through hole portion. Intersect to make an angle greater than 90 ° and less than 270 °,
In the through hole portion, when the substrate is viewed from a direction orthogonal to the substrate surface, an angle formed between an end portion on the through hole portion side of the first conductive pattern and the through hole portion is 90 °. An electro-optical device that is inclined so as to exceed. An electronic apparatus comprising the electro-optical device according to claim 10.

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