JP4535588B2 - Circuit boards and electronic devices - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flexible circuit board, and more particularly to a flexible circuit board with improved alignment marks for mounting an element chip such as an IC, a memory, or a controller.
[0002]
The present invention also relates to an electronic device as a device such as a mobile phone, an electronic notebook, or a portable information terminal using such a flexible circuit board, or an electronic device as an electronic component such as a liquid crystal display device or other display device. .
[0003]
[Prior art]
A conventional structure for mounting an IC on a flexible circuit board will be described.
The flexible circuit board goes through the following steps.
A polyimide varnish is applied on a copper foil having a thickness of 4 to 12 μm, a polyimide film having a thickness of 20 to 30 μm is formed on the copper foil, the copper foil is then etched into a desired wiring pattern, and then coated with a resist. At this time, in the flexible circuit board, the resist is removed so that the external connection terminals connected to other boards are exposed. Further, the resist is also removed in the vicinity of the IC connection terminal that is electrically connected to the IC.
[0004]
FIG. 2 is a schematic view of a conventional flexible circuit board obtained through the above steps.
A predetermined wiring pattern is formed on the surface of the film 1, a resist 2 is coated on the wiring pattern, and a resist removal portion 3 for mounting an IC is provided in the resist 2. An IC connection terminal 4 is formed in the resist removal portion 3, an external connection terminal 5 is formed in an outer region of the resist 2, and leads 6 for connecting the IC connection terminal 4 and the external connection terminal 5 are connected. It is interposed between the film 1 and the resist 2.
[0005]
In the flexible circuit board having this configuration, it is necessary to carry out with high accuracy in order to mount the IC.
[0006]
For this purpose, along with the formation of the wiring pattern, an alignment mark 7 is provided on the flexible circuit board, and oblique illumination is applied to the alignment mark 7 to recognize the image, thereby aligning the IC and the flexible circuit board. I was doing it.
[0007]
In that case, the resist is also removed from the portion of such an alignment mark 7.
[0008]
However, according to the flexible circuit board having the above configuration, the copper foil is exposed to the air for the IC connection terminal 4, the external connection terminal 5, and the alignment mark 7 from which the resist is removed. Corrosion occurred, resulting in problems such as disconnection of the wiring pattern.
[0009]
In order to solve this problem, a technique for preventing corrosion by applying electrolytic plating of Au to the IC connection terminal 4, the external connection terminal 5, and the alignment mark 7 has been proposed.
[0010]
This point will be further explained with reference to FIG. 2. The external connection terminal 5 formed in the outer region of the resist 2 is further provided with an electroplating pattern 8 to be connected to all the leads 6 and covered with the resist 2. Electrolytic plating of Au is performed on the portion that has not been formed, and then cut with a cut line 9 to exclude the pattern 8 for electrolytic plating, and a flexible circuit board is provided.
[0011]
The alignment mark 7 is also electroplated in the same manner. For this purpose, the electroplating of Au is performed by connecting to the adjacent lead 6.
[0012]
However, even after this electrolytic plating, if it is connected to the lead 6 as it is, external noise enters the wiring pattern connected from the alignment mark not covered with the resist, or from the wiring pattern via the alignment mark. There is a problem such as current leakage, which causes the quality to deteriorate.
[0013]
Therefore, the connection connecting the alignment mark 7 and the lead 6 is cut by providing a cut hole 10 after electrolytic plating of Au.
[0014]
[Problems to be solved by the invention]
However, in the conventional flexible circuit board having the above-described configuration, by providing the cut hole 10, a space for that is required, and the outer size of the flexible circuit board is increased in order to secure the space. We could not meet the market needs for high-density wiring and low cost.
[0015]
In addition, when the cut hole 10 is formed in the vicinity of the IC, the strength of the flexible circuit board mounted with the IC is lowered, thereby reducing the mounting accuracy.
[0016]
Accordingly, the present invention has been completed in view of the above description, and an object thereof is to provide a flexible circuit board that achieves miniaturization, high-density wiring, and low cost.
[0017]
Another object of the present invention is to provide a flexible circuit board with high quality and high reliability by increasing the strength of the circuit board itself and increasing the mounting accuracy.
[0018]
Still another object of the present invention is to provide an electronic device using the flexible circuit board of the present invention.
[0019]
[Means for Solving the Problems]
Circuit board of the present invention, the substrate and, provided on the substrate, the element mounting area from the first element connection terminal, located in front Symbol element mounting area having a rectangular element mounting area for mounting the device with it is drawn through the long side of a first wiring pattern group having a plurality of first wiring pattern for applying the output voltage from the device, provided on the substrate, placed in front Symbol device mounting region A second wiring pattern group having a plurality of second wiring patterns that are pulled out from the second element connection terminal to be applied through the short side of the element mounting region and apply an output voltage from the element; An alignment mark provided on the substrate and for aligning the element and the element mounting region, and an alignment mark provided on the substrate and connected to the alignment mark. The alignment mark and the alignment mark lead-out wiring are electrically insulated from the first wiring pattern group and the second wiring pattern group and outside the element mounting region. In addition, it is located between the first wiring pattern group and the second wiring pattern group in plan view.
[0020]
An electronic device of the present invention includes the circuit board of the present invention and an element mounted on an element mounting region of a base included in the circuit board.
[0021]
Further, it is not necessary to route the pattern around the cut hole, and the design efficiency is improved.
[0022]
Furthermore, the number of steps from the mother film increases due to the high-density wiring, thereby reducing the manufacturing cost and providing a low-cost flexible circuit board.
[0023]
In addition, a reduction in strength of the flexible circuit board due to the presence of the cut hole is prevented, thereby increasing the mounting accuracy of the element chip and improving the reliability of the product.
[0024]
In addition, the electronic device of the present invention is provided with the flexible circuit board of the present invention on which an element chip is mounted on another board, and the wiring pattern formed on the other board and the external connection of the flexible circuit board By connecting a terminal and transmitting the output signal of the element chip to another substrate, the use of a flexible circuit board that does not have a cut hole in this way increases the strength of the substrate itself and allows flexible The mounting accuracy of the circuit board with respect to another board is increased, and a highly reliable electronic device is provided.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS.
FIG. 1 is a schematic view of a flexible circuit board according to the present invention. FIG. 3 is a schematic diagram of a liquid crystal display device to which a flexible circuit board is connected.
(Flexible circuit board of the present invention)
In producing a flexible circuit board, a varnish of polyimide is applied on a copper foil having a thickness of 4 to 12 μm, a polyimide film having a thickness of 20 to 30 μm is formed on the copper foil, and then the copper foil is etched into a desired wiring pattern. Thereafter, the resist is coated, and at that time, the resist is removed so that the external connection terminals connected to the other substrate are exposed in the flexible circuit board, and the IC as the element chip is electrically connected. The resist is also removed in the vicinity of the IC connection terminal that is conductive.
[0026]
In addition, when the pattern pitch becomes fine, it is advantageous that the copper foil is thinner. Also, the polyimide film is excellent in bendability when it is thinned.
[0027]
In this example, copper foil is used, but instead of this, copper may be deposited on a polyimide film to form a film substrate.
[0028]
FIG. 1 is a schematic view of the flexible circuit board of the present invention obtained through such steps.
[0029]
A predetermined wiring pattern is formed on the surface of the film 1, a resist 2 as the protective film is coated on the wiring pattern, and a resist removing portion 3 for mounting IC is provided in the resist 2. The IC connection terminal 4 is formed on the resist 2, the external connection terminal 5 is formed in the outer region of the resist 2, and the leads 6 for connecting the IC connection terminal 4 and the external connection terminal 5 are connected to the film 1 and the resist 2. Between.
[0030]
An IC mounting alignment mark 11 is formed on the resist 2, and an IC mounting alignment mark lead wire 12 is provided on the lead 6, and one end of the IC mounting alignment mark lead wire 12 is connected to the IC mounting alignment mark 11. The other end extends in the vicinity of the external connection terminal 5.
[0031]
Further, the external connection terminal 5 formed in the outer region of the resist 2 is further connected to the electrolytic plating pattern 8, thereby connecting all the leads 6.
[0032]
The other end of the IC mounting alignment mark lead wiring 12 is also connected to the electrolytic plating pattern 8.
[0033]
Then, the electrolytic plating of Au is performed on the portion not covered with the resist 2, that is, the other end of the IC connection terminal 4, the external connection terminal 5, and the IC mounting alignment mark lead-out wiring 12.
[0034]
This electrolytic plating is also performed on the wiring portion existing on the IC mounting alignment mark 11.
[0035]
Thereafter, the flexible circuit board of the present invention is obtained by punching with a metal mold and cutting with the cut wire 9 to exclude the electrolytic plating pattern 8.
[0036]
Thus, according to the flexible circuit board of the present invention, the IC mounting alignment mark 11 is formed on the resist 2, and the IC mounting alignment lead wire 12 is provided along the lead 6, and one end of the IC mounting alignment lead wire 12 is provided. Is extended to the IC mounting alignment mark 11, the other end is extended to the vicinity of the external connection terminal 5, and electrolytic plating is performed on the portion of the wiring pattern where the resist 2 is not coated. Thus, the cut holes used in the conventional flexible circuit board are no longer necessary, and this enables high-density wiring along with miniaturization.
[0037]
Further, there is no need to route the pattern around the cut hole, the design efficiency is improved, and the number of steps taken from the mother film is increased by the high-density wiring, thereby reducing the manufacturing cost.
[0038]
Furthermore, the strength reduction of the flexible circuit board due to the presence of the cut hole is prevented, and the strength of the circuit board itself can be increased to improve the mounting accuracy.
[0039]
It should be noted that the present invention is not limited to the above embodiment, and various modifications and improvements can be made without departing from the scope of the present invention. For example, in this example, the resist 2 is formed, and then the electrolytic plating of Au is performed on the IC connection terminal 4, the external connection terminal 5, the IC mounting alignment mark 11, etc. that are not covered with the resist 2. Instead, before the resist 2 is coated, the wiring pattern is previously subjected to electrolytic plating of Au, and then the resist 2 is coated, and the resist 2 is covered with the resist removing portion 3 for mounting the IC and the external connection terminal. 5 exposed portions, IC mounting alignment marks 11 and the like may be provided.
[0040]
Further, instead of the resist, another protective film such as a polyimide film may be formed.
[0041]
In this example, an IC is used as the element chip. However, various element chips such as a memory and a controller may be used instead.
[0042]
(Electronic device of the present invention)
Examples of the electronic device include an electronic device as an electronic device such as a mobile phone, an electronic notebook, and a portable information terminal using a flexible circuit board. In addition, there are electronic devices such as liquid crystal display devices and other display devices.
[0043]
In the present invention, it is most effective in further downsizing an already miniaturized electronic device, and the effect is remarkable because the cut hole used in the conventional flexible circuit board is no longer necessary.
[0044]
Hereinafter, an example of the electronic device of the present invention will be described.
3 and 4 show a liquid crystal display device using the flexible circuit board of the present invention. FIG. 3 is a plan view thereof, and FIG. 4 is a sectional view thereof.
[0045]
This liquid crystal display device has a structure in which the flexible circuit board 1 of the present invention is connected to a liquid crystal cell 14 in which a liquid crystal material is sealed between two glass substrates on which wiring patterns are formed.
[0046]
A driver IC 13 for driving the liquid crystal cell 14 is mounted on the film 1 of the flexible circuit board, and the output voltage of the driver IC 13 is applied to the liquid crystal cell 14 via the external connection terminal 5 to perform display. It has a structure.
[0047]
【The invention's effect】
As described above, according to the circuitry substrate of the present invention, a substrate having a rectangular element mounting area for mounting the device, provided on a substrate, the first element connection terminal located in the device mounting region A first wiring pattern group having a plurality of first wiring patterns for applying an output voltage from the element is drawn through the long side of the element mounting area, and is provided on the substrate and positioned in the element mounting area. A second wiring pattern group having a plurality of second wiring patterns which are pulled out from the second element connection terminal via the short side of the element mounting region and apply an output voltage from the element; And an alignment mark for aligning the element and the element mounting region, and an alignment mark lead wiring provided on the substrate and connected to the alignment mark. The alignment mark and the alignment mark lead-out wiring are electrically insulated from the first wiring pattern group and the second wiring pattern group, and are outside the element mounting region and in plan view with the first wiring pattern group. since it situated between the second wiring pattern group, cut holes used in conventional circuits the substrate becomes unnecessary, which enables high-density wiring, also, necessary to route a pattern while bypassing the cut hole no, improved design efficiency further number taken from the mother substrate is increased by high-density wiring, thereby manufacturing cost is reduced, as a result, miniaturization, times that achieved high-density wiring and cost A road board could be provided.
[0048]
In the present invention, prevents strength reduction of the circuit board due to the presence of cut holes, to increase the strength of the circuit board itself, increasing the mounting accuracy, whereby the high-quality and highly reliable circuits board is able to provide.
[0049]
In the electronic device of the present invention, use a circuit board of the present invention, since including a device mounted on the element mounting area of the substrate having the circuit board, and that is, thus the circuits board having no cut holes in be had, highly reliable electronic device is provided.
[Brief description of the drawings]
FIG. 1 is a schematic view of a flexible circuit board according to the present invention.
FIG. 2 is a schematic view of a conventional flexible circuit board.
FIG. 3 is a plan view of the electronic device (liquid crystal display device) of the present invention.
FIG. 4 is a cross-sectional view of an electronic device (liquid crystal display device) of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Film 2 ... Resist 3 ... Resist removal part 4 ... IC connection terminal 5 ... External connection terminal 6 ... Lead 7 ... Alignment mark 8 ... Electrolytic plating pattern 9 ... Cut wire 11 ... IC mounting alignment mark 12 ... IC On-board alignment mark lead-out wiring 13... Driver IC
14 ... Liquid crystal cell

Claims (2)

A substrate having a rectangular element mounting region for mounting elements;
Wherein provided on a substrate as would the first element connection terminal, located in front Symbol device mounting region drawn through the long side of the element mounting area, a plurality for applying the output voltage from the device first A first wiring pattern group having one wiring pattern;
Wherein provided on a substrate, with the second element connection terminal, located in front Symbol device mounting region drawn through the short side of the element mounting area, a plurality for applying the output voltage from the device first A second wiring pattern group having two wiring patterns;
An alignment mark provided on the base and for aligning the element and the element mounting region;
An alignment mark lead-out line provided on the base body and connected to the alignment mark,
The alignment mark and the alignment mark lead wiring are electrically insulated from the first wiring pattern group and the second wiring pattern group, and are outside the element mounting region and in the plan view. A circuit board positioned between a wiring pattern group and the second wiring pattern group. A circuit board according to claim 1;
And an element mounted on an element mounting region of a base of the circuit board.

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