KR20000048248A - Circuit Board, And Display Device Using The Same And Electronic Equipment - Google Patents

Abstract

PURPOSE: A circuit board and a display device and an electronic device using thereof are provided to improve the adhesion of an adhesive resin as to a base substrate, to improve the electrical connection reliability of a semiconductor chip and an interconnection substrate, to prevent the lowering of the performance or the reliability of the semiconductor chip and to reduce the invasion of humidity to the adhesion region in the base substrate. CONSTITUTION: In a circuit board where a semiconductor chip is installed on a base substrate using an adhesive resin, the circuit board improves the adhesion of the adhesive resin and the electrical connection reliability of the semiconductor chip and the base substrate. An IC chip(450) is installed by inserting an anisotropic conductive film, by forming an input interconnection(420a) and an output interconnection(420b) and a dummy interconnection layer(422) without an adhesion layer, on an IC chip installation region of a base film(410). The dummy interconnection layer is insulated from the input interconnection, the output interconnection and electrodes(450a,450b) of the IC chip, and comprises a plurality of open apertures(422a).

Description

Circuit Board, And Display Device Using The Same And Electronic Equipment

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board formed by flip chip mounting a semiconductor chip on a base substrate, a display device and an electronic device using the circuit board.

In recent years, IC chips have been used for flexible printed circuit (FPC) substrates for reasons such as miniaturization and thinning of substrates, adaptation to bendable structures, and high productivity through a roll-to-roll process. Direct mounting of electronic components has been made to be used. Moreover, since this technique does not require internal conductors as in the Tape Automated Bonding (TAB) technique, the copper foil becomes thinner, so that the fine pitch of the wiring is easy.

Fig. 16 is a cross-sectional view showing a conventional structure when the electronic component is mounted on the FPC board. As shown in this figure, the input wire 450a of the IC chip 450 and the input wiring 420a previously formed in the base film 410 are connected through the conductive particles 21 dispersed in the adhesive resin 19. Similarly, the output electrode 450b of the IC chip 450 and the output wiring 420b previously formed on the base film 410 are electrically connected to each other through the conductive particles 21 dispersed in the adhesive resin 19. It is joined.

However, since an organic film such as PI (polyimide) is generally used for the base film 410, which is the base member of the FPC substrate, the base from the opposite side of the mounting surface (lower side in the drawing). Moisture that penetrates the film 410 reaches the wiring forming surface of the IC chip 450, thereby deteriorating the reliability of the IC chip or leaking light due to light transmitted through the base film 410. (light leakage) has the disadvantage that the performance of the IC chip is reduced. And this fault becomes more remarkable when the base film 410 is made thin.

Moreover, since it is common to use polyimide etc. with low surface wettability for the base film 410 which is the base member of an FPC board | substrate, the bonding strength of adhesive resin is very weak.

Further, under the influence of the difference in the coefficient of thermal expansion of each material of the base film 410, the IC chip 450, and the adhesive resin 19, stress is concentrated on the adhesive interface over time, and thus the adhesive force is further lowered. There was a problem that a poor connection between the electrode of the IC chip 450 and the wiring of the FPC board is likely to occur. In particular, when the base film is a thin material having flexibility such as polyimide, there is a penetration of humidity on the base film side, and a decrease in adhesion force occurs, and the wiring of the electrode of the IC chip 450 and the FPC substrate is prevented. The problem which a connection connection tends to produce was more remarkable.

This invention is made | formed in view of the above, The objective is the circuit board of the structure which mounted the semiconductor chip on the base board using the adhesive resin, The circuit board which can solve any of the following problems. And a display device and an electronic device using the same.

1) Improve the adhesive strength of the adhesive resin to the base substrate.

2) The electrical connection reliability of a semiconductor chip and a wiring board is improved.

3) To prevent deterioration in the performance or reliability of semiconductor chips.

4) On the base substrate side, invasion of moisture into the bonding region is reduced.

(1) The circuit board according to the present invention,

A wiring board having an insulating base member and a plurality of substrate-side terminals provided on the base member;

A plurality of semiconductor side terminals, the semiconductor side terminals being electrically connected to the substrate side terminals, and having a semiconductor chip mounted on the wiring board,

The wiring board includes a dummy wiring layer insulated from the substrate-side terminal and the semiconductor-side terminal in an area in which the semiconductor chip is mounted and inside the substrate-side terminal.

According to the present invention, a part of the moisture that penetrates through the base member is blocked by the dummy wiring layer on the surface opposite to the mounting surface of the semiconductor chip. Therefore, the possibility that the board | substrate side terminal, the semiconductor side terminal, etc. of the area | region in which the semiconductor chip was mounted in the wiring board will cause the fall of reliability by moisture is reduced. In the case where the semiconductor chip is mounted on the wiring board, the board-side terminal, the semiconductor-side terminal, and the wiring pattern are usually in a narrow pitch in the mounting area, and short circuits or pseudo short circuits are generated due to moisture or the like. There is this. In the circuit board of this invention, occurrence of such a problem can be reduced.

In a semiconductor chip, current leakage may occur due to light intrusion. However, since the amount of light penetrating through the base member is reduced by the dummy wiring layer, the performance degradation of the semiconductor chip due to such leakage of current can be suppressed.

(2) The circuit board which concerns on this invention further has the resin sealing part which seals the part in which the said semiconductor side terminal and the said board side terminal were electrically connected, and joins the said semiconductor chip to the said wiring board.

According to the present invention, in the region where the semiconductor chip is mounted on the surface of the base member, by providing a dummy wiring layer in an inner portion of the substrate side terminal, the adhesion area of the resin encapsulation portion to the wiring substrate can be increased, thereby. Adhesion can be improved. As a result, the adhesive force of the resin encapsulation portion to the wiring board is increased, and the connection reliability between the semiconductor side terminal and the board side terminal can be improved. Furthermore, in order to prevent the dummy wiring layer from invading the humidity on the base substrate side, it is possible to suppress a decrease in the adhesive force of the resin encapsulation portion due to the change in time. Furthermore, since the dummy wiring layer can be formed of a material whose adhesiveness to the resin encapsulation portion is higher than that of the base member, the adhesive force of the resin encapsulation portion to the wiring substrate can be increased.

(3) The circuit board according to the present invention,

The resin encapsulation portion is formed of an anisotropic conductive film in which conductive particles are dispersed and mixed in a resin,

The semiconductor side terminal and the substrate side terminal are electrically connected by the conductive particles.

Thus, when a semiconductor chip and a wiring board are bonded together by an anisotropic conductive film, the process corresponded to two processes, a bonding process in TAB (Tape Automated Bonding) mounting, and a mold process, can be performed as one process, There is an advantage that the manufacturing process can be shortened.

(4) In the circuit board according to the present invention, the dummy wiring layer is formed of the same material as the terminal on the board side.

For example, when a board | substrate side terminal is formed using Cu (copper), a dummy wiring layer is formed with Cu simultaneously with the board | substrate side terminal. In addition, when the board | substrate side terminal is formed by performing Ni plating, Au plating, etc. on the surface of Cu, a dummy wiring layer is also formed by giving the same plating process to the surface of Cu.

Thereby, it becomes possible to form a dummy wiring layer and a board | substrate side terminal simultaneously, and can simplify a manufacturing process of a circuit board.

(5) In the circuit board according to the present invention, the base member is formed of a material having flexibility.

For example, the base member is formed of a material having flexibility such as polyimide. When the base member is formed of a thin material having flexibility, the base member is likely to be deformed by external stress. Therefore, in the case where the semiconductor chip is bonded to the wiring board by the resin encapsulation portion, the stress is locally concentrated at the adhesive interface of the base member and the resin encapsulation portion, and thus the adhesive force is lowered, resulting in poor connection between the semiconductor side terminal and the substrate side terminal. Easy to occur In addition, when the base member is a thin material such as polyimide, a decrease in adhesive force occurs due to the ingress of moisture on the base member side, and as a time passes, poor connection between electrode terminals is likely to occur. Therefore, in a circuit board in which a semiconductor chip is mounted on a wiring circuit using such a flexible base member using a bonding agent, as in the present invention, in the area where the semiconductor chip is mounted on the surface of the base member, the substrate side terminal is provided. When the dummy wiring layer is provided on the inner portion, the adhesive force of the resin encapsulation portion to the base member is improved, and the connection reliability between the semiconductor side terminal and the substrate side terminal can be improved.

(6) In the circuit board according to the present invention, the base member, the dummy wiring layer, and the board-side terminal are directly joined without interposing an adhesive layer.

Thus, when the dummy wiring layer and the board side terminal are formed directly on the base member without interposing the adhesive layer, it is possible to reduce the current leakage caused by the adhesive, prevent the swell of the adhesive, and improve the flexibility of the wiring board. It becomes possible.

(7) The circuit board according to the present invention,

In the plane, the base member is exposed in contact with the dummy wiring layer, and further has an open portion continuous to the exposed area of the base member,

The dummy wiring layer is in contact with only the opening in a plane.

According to the present invention, when the semiconductor chip is pressed against the wiring board by sandwiching the adhesive resin formed from the resin encapsulation portion, the adhesive resin is pushed to the outer portion through the opening portion, so that residual stress is generated in the resin encapsulation portion. Can be reduced, and the thickness of the resin encapsulation can be made uniform. As a result, the twist of the base member is eliminated and the residual stress thereof can also be reduced, so that the connection reliability is improved.

(8) In the circuit board according to the present invention, the dummy wiring layer is formed as one continuous region.

(9) In the circuit board according to the present invention (8), the dummy wiring layer is formed as a serpentine region.

(10) In the circuit board according to the present invention (8), the dummy wiring layer has a shape in which a plurality of first line segment regions in parallel with each other and a second line segment region extending across the first line segment region are combined. It is formed as an area.

(11) In the circuit board according to the present invention, the dummy wiring layer has one or more openings in any one of (1) to (6).

According to this invention, the dummy wiring layer which has an opening in the area | region where a semiconductor chip is mounted is formed in the surface of a base member. Therefore, when the semiconductor chip is joined to the wiring board by the resin encapsulation part, the joining interface of the wiring board and the resin encapsulation part becomes uneven, and the strength is improved by mechanically engaging the bonding force between the resin encapsulation part and the wiring board. Since this is added, the reliability of the joining is greatly improved.

(12) In the circuit board according to the present invention, in any one of (1) to (6), the dummy wiring layer is formed as a plurality of dummy wiring regions spaced apart by a region where the base member is exposed.

According to the present invention, when the semiconductor chip is bonded to the wiring board by the resin encapsulation part, the joining interface of the wiring board and the resin encapsulation part becomes uneven, and is caused by mechanically engaging the bonding force between the resin encapsulation part and the wiring board. Since the strength improvement is applied, the reliability of the joint is greatly improved.

(13) In the circuit board according to the present invention, in (12), the plurality of dummy wiring regions are partially connected. Thereby, it becomes possible to improve the adhesiveness of the resin sealing part and wiring board in the case where a semiconductor chip is bonded to a wiring board by the resin sealing part.

(14) In the circuit board according to the present invention, in any one of (1) to (6), the dummy wiring layer has one or more recessed portions whose thickness of the wiring layer is thinner than that of other regions of the dummy wiring layer.

According to the present invention, when the semiconductor chip is bonded to the wiring board by the resin encapsulation part, the joining interface of the wiring board and the resin encapsulation part becomes uneven, and is caused by mechanically engaging the bonding force between the resin encapsulation part and the wiring board. Since the strength improvement is added, the reliability of the joint is improved.

(15) The display device according to the present invention includes the circuit board according to any one of (1) to (14),

The said circuit board has a flat panel provided with the connection terminal electrically connected.

(16) The display device according to the present invention is as (15),

It is a liquid crystal panel which has a pair of board | substrates which the said flat panel opposes, and the liquid crystal enclosed between the pair of board | substrates,

The connection terminal is formed on at least one of the pair of substrates.

(17) The electronic device according to the present invention has the display device according to (15) or (16) as display means.

1 is a plan view showing a circuit board according to a first embodiment of the present invention.

2 is a cross-sectional view at a position along the line A-A in FIG.

3 is an exploded perspective view showing two FPC substrates having a structure shown in FIGS. 1 and 2 and a liquid crystal panel;

4 is a partially broken perspective view illustrating a configuration of a liquid crystal panel according to the first embodiment.

5 is a cross-sectional view showing a configuration of a liquid crystal projector that is an example of an electronic apparatus to which the liquid crystal device according to the first embodiment is applied.

Fig. 6 is an external view showing a mobile phone which is another example of an electronic apparatus to which the liquid crystal device according to the first embodiment is applied.

7 is a plan view illustrating a circuit board according to a second embodiment.

8 is a cross-sectional view at a position along the line A-A in FIG.

9 is a plan view illustrating a circuit board according to a third embodiment.

10 is a sectional view at a position along the line A-A in FIG.

11 is an exploded perspective view showing a liquid crystal device according to a fourth embodiment.

12 is a partial cross-sectional view showing a liquid crystal device according to a fourth embodiment.

Fig. 13 is a partial plan view showing the circuit board of the fourth embodiment as a state before the IC chip 11 is mounted.

Fig. 14 is a partial plan view showing the circuit board of the fifth embodiment as a state before the IC chip 11 is mounted.

FIG. 15 is a partial plan view showing the circuit board of the sixth embodiment as a state before the IC chip 11 is mounted. FIG.

16 is a cross-sectional view showing a conventional circuit board.

※ Explanation of code for main part of drawing ※

1,10: liquid crystal device 2, 100: liquid crystal panel

3: circuit board 6a, 6b: board

12: anisotropic conductive film 13: wiring board

19: adhesive resin 21: conductive particles

23A, 23B, 23C, 422, 424: dummy wiring layer

400: FPC board (wiring board) 45O: IC chip (semiconductor chip)

EMBODIMENT OF THE INVENTION Hereinafter, preferred embodiment of this invention is described more concretely, referring drawings.

1. <First Embodiment>

1.1 Circuit Board

First, the mounting structure in the circuit board which concerns on 1st Embodiment of this invention is demonstrated. 1 is a plan view showing a part of this circuit board, and FIG. 2 is a cross-sectional view at a position along the line A-A in FIG. 1 and 2, the flexible printed circuit (FPC) substrate 400 as a wiring board firstly forms a copper thin film by sputtering or vapor deposition on both surfaces of the base film 410 as a base member having insulation and flexibility. Second, the copper thin film is patterned into a predetermined shape by conventional photolithography techniques, etching, or the like, and third, copper plating is performed on the patterned copper thin film. Moreover, after apply | coating the polyamic acid which is a precursor of polyimide to copper foil as FPC board | substrate 400, it heat-polymerizes and polyimide-forms, and this polyimide is formed as a base film 410 as a wiring board. You may use one.

Moreover, as FPC board | substrate 40O, what laminated | stacked and formed the copper foil on both surfaces of the base film 410 by the adhesive agent, and then patterned in the predetermined shape may be used, As mentioned above, the wiring pattern for the base film 410 is mentioned. Is advantageous in that the current is not leaked by the adhesive in the adjacent wiring pattern, the swelling of the adhesive does not occur, and the flexibility of the FPC substrate 400 is improved.

As the base film 410 which is the base member, other organic films such as polyethylene terephthalate and polyester may be used in addition to polyimide. On the other hand, the wiring pattern formed on the FPC board 400 includes an input wiring 420a, an output wiring 4200b, a dummy wiring layer 422, and the like.

On the other hand, the rectangular chip-shaped IC chip 450 (semiconductor chip) is provided with a large number of input electrodes 450a and output electrodes 450b as semiconductor-side terminals on the peripheral edge of one surface thereof, and at the same time, the input electrodes 450a and outputs are provided. It is mounted on the FPC board 400 with the surface on which the electrode 450b is formed downward. Each input electrode 450a and each output electrode 450b are formed with a bump (protrusion electrode) made of Au or the like in advance. In the bonding between the IC chip 450 and the FPC board 400, first, the IC chip 450 attaches the conductive particles 21 to a resin 19 for bonding such as epoxy at a predetermined position of the FPC board 400. An anisotropic conductive film (ACF) having a uniformly dispersed film shape is sandwiched therebetween. Thereafter, the IC chip 450 is pressed against the FPC substrate 400 in a heated state, and bonded to the FPC substrate 400 with a pressurized and heated anisotropic conductive film therebetween. In this way, a circuit board on which the IC chip 450 as the semiconductor chip is mounted is formed on the FPC board 400 as the wiring board.

In this mounting, as shown in FIG. 2, the input electrode 450a is connected to the input wiring 420a (substrate side terminal), and the output electrode 450b is connected to the output wiring 420b (substrate side terminal), respectively. It becomes electrical connection across the electroconductive particle 21 disperse | distributed in the suitable ratio in resin 19 for bonding, such as an epoxy resin and a photocurable resin, in between. Here, the adhesive resin 19 protects the surface on which the input electrode 450a and the output electrode 450b are formed in the IC chip 450 from moisture, contamination, stress, and the like, thereby protecting the IC chip 450 from the FPC substrate. Also serves as a resin encapsulation portion to be bonded to (400).

Thus, when the IC chip 450 and the FPC board 400 are bonded by an anisotropic conductive film, the bonding process and the mold process in conventional TAB mounting can be performed as one process, and the manufacturing process can be shortened. There is an advantage.

By the way, the dummy wiring layer 422 in this embodiment is formed in the area | region in which the IC chip 450 is mounted so that neither the input wiring 420a which is a board | substrate side terminal nor the output wiring 420b may contact. As shown to FIG. 1 and FIG. 2, it is formed provided with the some opening part 422a. For this reason, in the area | region where the IC chip 450 is mounted, the area by which the base film 410 with the smooth surface is exposed is reduced, and the dummy wiring layer 422 which has many opening parts 422a exists. Therefore, in addition to the adhesive strength of the base film 410 and the adhesive resin 19, the improvement of the strength by the mechanically interlocking structure by the dummy wiring layer 422 is brought about, so that the adhesive resin 19 and The bonding strength with the wiring board 400 is remarkably improved.

In addition, due to the presence of the dummy wiring layer 422, in the region where the IC chip 450 is mounted, the area where the base film 410 is exposed is minimized due to the absence of copper foil. Therefore, in FIG. 2, moisture penetrated from the lower side of the base film 410 is prevented by the dummy wiring layer 422 and hardly penetrates to the adhesive resin 19 that is a resin encapsulation portion. Thereby, the fall of the reliability of the IC chip 450 is prevented. In addition, since the light penetrating from the lower side of the base film 410 in the drawing is almost blocked by the dummy wiring layer 422 in the drawing and does not penetrate into the electrode formation surface (wiring formation surface) of the IC chip 450, The deterioration of the IC chip 450 due to leakage of photocurrent is also prevented.

Moreover, in the said embodiment, the joining of the input electrode 450a and the input wiring 420a, and the joining of the output electrode 450b and the output wiring 420b are each electroconductive particle 21 disperse | distributed in the adhesive resin 19, respectively. ), I.e., an anisotropic conductive film is interposed therebetween, but other bonding modes may be used. For example, Au plating is performed on the copper foil forming the input wiring 420a and the output wiring 420b, and the Au-Au junction is also formed between the Au bumps of the input electrode 450a and the output electrode 450b. good. Moreover, tin plating is performed on the copper foil which forms the input wiring 420a and the output wiring 420b, and this and Au bumps of the input electrode 450a of the IC chip 450 and the output electrode 450b are heated by contact. You may combine Au-Sn process by doing it. Moreover, the copper foil which forms the input wiring 420a and the output wiring 420b is made into the pattern which can be solder-bonded, and the bump of the input electrode 450a and the output electrode 450b of the IC chip 450 is carried out. The material may be used as the solder or as the solder-solder joint. In this bonding, the IC chip 450 is molded by using the sealing material as the resin encapsulation portion.

In addition, what is mounted on the FPC board 400 is not limited to the IC chip 450. For example, any other active element or non-active element may be used as long as the element is likely to be affected by moisture or light penetrated through the base film 410 when attached to the FPC board 400.

Further, the adhesive resin 19 in which the conductive particles 21 are dispersed is concentrated on the input electrode 45Oa and the output electrode 450b of the IC chip 450, and the input electrode 450a and the input wiring 420a and After joining the output electrode 450b and the output wiring 420b, respectively, you may make these joining parts mold with a sealing material as a resin sealing part.

In addition, since the dummy wiring layer 422 is not used as wiring, if the potential is not determined, a capacitance component is generated and is not suitable. For this reason, it is suitable to connect to ground level wiring actually.

1.2 Display

As described above, when the IC chip 450 is mounted on the FPC board 400, the time required for the process becomes constant regardless of the number of connection electrodes of the IC chip 450 as compared with wire bonding. For this reason, when the number of electrodes of the IC chip 450 is very large, the productivity is remarkably improved. Here, as an IC chip having a very large number of electrodes, for example, a driving circuit (driver) for driving a data line or a scanning line in a display device is mentioned. Therefore, the liquid crystal device using the FPC board | substrate with which such a driver was mounted as an application example of such a mounting structure is demonstrated.

As shown in FIG. 3, the liquid crystal device 1 mainly includes the liquid crystal panel 100, two FPC boards 400X and 400Y bonded to the liquid crystal panel 100, and these FPC boards 400X and 400Y. The control circuit board (not shown) connected to () is comprised. Among them, the liquid crystal panel 100 projects the terminal substrates 216 and 316 to the outside, and the element substrate 200 on which a plurality of data lines and the like are formed and the opposing substrate 300 on which a plurality of scanning lines and the like are formed. It is formed in the structure which joined together in the state which the electrode formation surface opposing.

In detail, as shown in FIG. 4, a plurality of pixel electrodes 234 arranged in a matrix shape and a data line (signal line) extending in a column direction on the opposite surface of the device substrate 200 to the opposing substrate 300. 212 are formed, and each of the columns of pixel electrodes 234 is connected to one data line 212 with a thin film diode (TFD) element 220 interposed therebetween. Here, the TFD element 220 is composed of the first metal film 222, the oxide film 224 and the second metal film 226 obtained by anodizing the first metal film 222, and the metal It consists of sandwich structure of / insulator / metal. For this reason, the TFD element 220 has a switching characteristic as a positive bidirectional diode.

On the other hand, in the opposing surface of the opposing substrate 300, the scanning line 312 extends in a row direction orthogonal to the data line 212, and is arranged to be the opposing electrode of the pixel electrode 234 on the opposing surface of the element substrate 200. In addition, although the illustration of the color filter is abbreviate | omitted, it is provided corresponding to each pixel electrode 234. As shown in FIG. For this reason, the liquid crystal cell corresponding to one pixel comprises the pixel electrode 234, the scanning line 312 which is an opposing electrode, and the liquid crystal charged between these board | substrates.

The element substrate 200 and the counter substrate 300 maintain a constant gap (gap) by a sealant applied along the periphery of the substrate and a spacer that is appropriately dispersed, and, for example, TN ( Twisted Nematic type liquid crystal is encapsulated. In addition, an alignment film or the like, which is polished in a predetermined direction, is provided on the opposing surfaces of the element substrate 200 and the opposing substrate 300, respectively, and on each rear surface thereof, polarizing plates in accordance with the alignment direction are provided (all of them). Not shown). However, when the polymer dispersed liquid crystal in which the liquid crystal is dispersed as microparticles in the polymer is used, the above-described alignment film, polarizing plate, or the like becomes unnecessary. In addition, when the polymer dispersed liquid crystal is used, the light utilization efficiency is increased, which is advantageous in terms of high luminance and low power consumption.

In such a configuration, the data line 212 and the scan line 312 are brought into a state where the liquid crystal layer and the TFD element 220 are electrically coupled at the intersection thereof. For this reason, when a voltage equal to or greater than the threshold is applied to the TFD element 220 by the scan signal applied to the scan line 312 and the data signal applied to the data line 212, the corresponding element is turned on and the corresponding element is turned on. The predetermined charge is accumulated in the liquid crystal layer connected to the element. Even if the element is turned off after charge accumulation, if the resistance of the liquid crystal layer is sufficiently high, the accumulation of charge in the liquid crystal layer is maintained. In this way, when the amount of charges to be stored by driving the TFD element 220 on and off is controlled, the alignment state of the liquid crystal is changed for each pixel, so that predetermined information can be displayed. At this time, since charges are accumulated in each liquid crystal layer for a partial period of time, the data lines 212 and the scan lines 312 are assigned to the plurality of pixels by time-selecting each scan line 312. In general, time-division multiplexing driving has become possible. In addition, the scan lines may be formed on the element substrate 200 and the data lines may be formed on the counter substrate by reversing the formation of the scan lines and the data lines.

By the way, although not shown in FIG. 3, the terminal region 216 of the element substrate 200 is provided with a data line terminal, which is a connection terminal for drawing each data line to the outside, while the terminal region of the opposing substrate 300 is provided. In 316, a scanning line terminal, which is a connecting terminal for drawing each scanning line to the outside, is provided below the substrate.

In addition, the FPC boards 400X and 400Y have the structure of the above-mentioned circuit board comprised including the FPC board 400, the IC chip 450, and the dummy wiring layer 422, for example. Among these, in the FPC board 400X, the driver 450X for driving each data line is an IC chip, and is mounted inverted up and down from FIG. For this reason, the dummy wiring layer 422X in the FPC board 400X is provided below in FIG. On the other hand, in the FPC board 400Y, the driver 450Y for driving each scan line is mounted as an IC chip in the same direction as the top and bottom of FIG. For this reason, the dummy wiring layer 422Y in the FPC board 400Y is provided above in FIG.

Here, in the FPC board 400X, a terminal located at one end thereof and further extending the input wiring is joined to the control circuit board, while a terminal located at the other end and extending the output wiring respectively is the element substrate 200. Is connected to a data line terminal, which is a connecting terminal formed in the terminal region 216 of FIG. Similarly, in the FPC board 400Y, terminals which are positioned at one end and each of which extends the input wiring are joined to the control circuit board, while terminals which are located at the other end and which respectively extend the output wiring are opposed to the substrate 300. Is connected to a scan line terminal which is a connecting terminal formed in the terminal region 316 of FIG.

With this configuration, the driver 450Y generates a scan signal in accordance with the control signal supplied from the control circuit board and supplies it to each scan line of the counter substrate 300. On the other hand, the driver 45OX supplies a data line corresponding to a control signal supplied from the control circuit board to each data line of the device substrate 200. In this case, as described above, in the drivers 450X and 450Y mounted on each of the FPC boards 400X and 400Y, deterioration in reliability and performance is prevented by the dummy wiring layers 422X and 422Y provided corresponding to the mounting area. .

In addition, as a liquid crystal panel, a passive matrix system having no TFD element or a scanning line and a data line are provided on an element substrate, and a pixel electrode is connected to the intersection portion via a TFT (Thin Film Transistor) element. Even a liquid crystal panel is applicable.

1.3 Electronic Devices

1.3.1 Projector

Next, the example which used the liquid crystal device 1 mentioned above in the display part of an electronic device is demonstrated. 5 is a plan view illustrating a configuration example of a projector using this liquid crystal panel as a light valve.

As shown in this figure, inside the projector 1100, a lamp unit 110 is formed of a white light source such as a halogen lamp. The projection light emitted from the lamp unit 110 is discharged by RGB {R; by four mirrors 1106 and two dichroic mirrors 1108 disposed in a light guide 1104; Red, G; Green, B; Blue} are separated into three primary colors and are incident on the liquid crystal panels 1110R, 1110B, and 1110G as light valves corresponding to the primary colors.

The liquid crystal panels 1110R, 1110B, and 1110G are the liquid crystal panels described above, which are driven by primary color signals of R, G, and B supplied from an image signal processing circuit (not shown) through the FPC boards 400X, 400Y, respectively. . Light modulated by these liquid crystal panels is incident on the dichroic prism 1112 in three directions. In this dichroic prism 1112, light of R and B is refracted at 90 degrees while light of G is straight. Therefore, as a result of combining the images of each color, the color image is projected onto the screen or the like through the projection lens 1114.

Here, since the light corresponding to each of the primary colors of R, G, and B is incident on the liquid crystal panels 1110R, 1110B, and 1110G by the dichroic mirror 1108, it is necessary to provide a color filter on the counter substrate 300. There is no.

1.3.2 Mobile Phones

FIG. 6 shows a cellular phone 30 which is another example in which the above-described liquid crystal device 1 is used for the display portion of an electronic device. The mobile phone 30 is constructed by storing various components such as an antenna 31, a speaker 32, a liquid crystal device 10, a key switch 33, a microphone 34, and the like in an external case 36 as a main body. do. Further, a control circuit board 37 mounted with a control circuit for controlling the operation of each component described above is provided inside the exterior case 36. The liquid crystal device 1 is comprised by the liquid crystal device 1 shown in FIG.

As the cellular phone 30, signals input through the key switch 33 and the microphone 34, received data received by the antenna 31, and the like are input to the control circuit on the control circuit board 37. Then, the control circuit displays images such as numbers, letters, drawings, and the like on the display surface of the liquid crystal device 1 based on the various input data, and further transmits transmission data from the antenna 31.

2. <2nd embodiment>

The second embodiment differs from the first embodiment in the shape of the dummy wiring layer. Other things are comprised similarly to 1st Embodiment, and the description is abbreviate | omitted. In addition, in drawing, each part same as 1st Embodiment is attached | subjected the same code | symbol as 1st Embodiment.

FIG. 7 is a plan view showing a mounting structure in the wiring board of the present embodiment, and FIG. 8 is a cross-sectional view at a position along the line A-A in FIG. 7. As shown in FIG. 7 and FIG. 8, in the dummy wiring layer 424 provided on the FPC board 402 according to the second embodiment, the slit 424a as a plurality of openings formed by removing copper foil is an IC chip 450. It is installed in the longitudinal direction of. For this reason, since the area | region in which the dummy wiring layer 424 was provided becomes uneven | corrugated shape from the IC chip 450, the adhesiveness of the IC chip 450 by the adhesive resin 19 improves like 1st Embodiment. do.

In the second embodiment, although the slit 424a provided in the dummy wiring layer 424 is the type of the IC chip 450, it may be in the transverse direction and crosswise in the longitudinal and transverse directions. It may be sufficient as it and may also be a diagonal direction further.

3. <Third Embodiment>

The third embodiment differs from the first embodiment in the shape of the dummy wiring layer. Other things are comprised similarly to 1st Embodiment, and the description is abbreviate | omitted. In addition, in the figure, the same code | symbol as 1st Embodiment is attached | subjected to each part same as 1st Embodiment.

In the second embodiment described above, while the adhesion of the IC chip 450 is improved, the area where the base film 410 is exposed in the region where the IC chip 450 is mounted due to the presence of the slit 424a is determined. Increases. For this reason, as a result of the increase in the amount of moisture and light penetrating the base film 410, there is a drawback that the reliability and performance of the IC chip 450 may be lowered as compared with the first embodiment.

Then, the mounting structure in the circuit board of 3rd Embodiment which improved the adhesiveness of IC chip 450 after ensuring the reliability, performance, etc. of IC chip 450 at the same level as 1st Embodiment is demonstrated. . FIG. 9 is a plan view showing the mounting structure of the circuit board, and FIG. 10 is a sectional view taken along the line A-A in FIG. As shown in FIG. 9 and FIG. 10, the dummy wiring layer 426 provided in the FPC board 404 in the third embodiment is provided with a plurality of slits 426a in the same manner as in the second embodiment. Unlike the embodiment, the copper foil is not removed from the slit 426a. That is, as apparent from FIG. 10, the thickness of the copper foil in the slit 426a is thin, but is not removed. For this reason, the area where the base film 410 is exposed in the region where the IC chip 450 is mounted is minimized, so that moisture and light penetrating the base film 410 are almost caused by the dummy wiring layer 426. It is stopped. As a result, similarly to the first embodiment, a decrease in the reliability and performance of the IC chip 450 is prevented. In addition, since the region where the dummy wiring layer 426 is provided becomes uneven when viewed from the IC chip 450, the adhesion of the IC chip 450 by the adhesive resin 19 is improved as in the first embodiment. .

In addition, such a dummy wiring layer 426 can be formed by the following method. For example, in FIG. 9, after forming the pattern of the copper foil which has the planar shape which added the area | region of the dummy wiring layer 426 and the area | region of the slit 426a, light etching (for the part corresponded to the slit 426a) light etching) or, on the contrary, after forming a pattern of copper foil having a planar shape in which the region of the dummy wiring layer 426 and the region of the slit 426a are added, the portion corresponding to the slit 426a. In addition, it can form by the method of affixing copper thickly by plating.

4. <4th embodiment>

4th Embodiment differs from 1st Embodiment in the shape of a dummy wiring layer, the arrangement | positioning of a semiconductor side terminal and a board | substrate side terminal, and the liquid crystal panel to which a circuit board is connected. Otherwise, it is comprised like 1st Embodiment and the description is abbreviate | omitted. In addition, in drawing, each part same as 1st Embodiment is attached | subjected the same code | symbol as 1st Embodiment.

11 is an exploded perspective view showing the liquid crystal device 1 according to the present embodiment. This liquid crystal device 1 is formed by connecting the circuit board 3 to the liquid crystal panel 2. In addition, illumination devices, such as a backlight, and other auxiliary equipment are attached to the liquid crystal panel 2 as needed.

The liquid crystal panel 2 has a pair of substrates 6a and 6b bonded by the sealing material 4, for example in a gap formed between them, a so-called cell gap, for example, STN (Super Twisted Nematic) A liquid crystal of the type is enclosed and formed. The substrates 6a and 6b are generally formed of a light transmissive material such as glass, synthetic resin, or the like. The polarizing plate 8 is adhere | attached on the outer surface of the board | substrate 6a and 6b.

An electrode 7a is formed on the inner surface of one substrate 6a, and an electrode 7b is formed on the inner surface of the other substrate 6b. The electrodes are formed in a stripe shape or letters, numbers, or other suitable pattern shape. In addition, the electrodes 7a and 7b are formed of a light transmissive conductive material such as, for example, indium tin oxide (ITO).

One board | substrate 6a has the protrusion part which protrudes from the other board | substrate 6b, and the some connection terminal 9 is formed in this protrusion part. The connection terminal 9 is formed at the same time as the electrode 7a is formed on the substrate 6a, for example, by ITO. The connecting terminal 9 includes a member integrally extending from the electrode 7a and a member connected to the electrode 7b by sandwiching a conductive material (not shown).

Incidentally, although the electrodes 7a and 7b and the connecting terminals 9 are actually formed on the substrate 6a and the substrate 6b at very narrow intervals, in FIG. The interval is enlarged and shown typically, and the other part is abbreviate | omitted as showing several of them. In addition, the connection state of the connection terminal 9 and the electrode 7a, and the connection state of the connection terminal 9 and the electrode 7b are also abbreviate | omitted in FIG.

The circuit board 3 mounts the liquid crystal drive IC chip 11 as a semiconductor chip at a predetermined position on the wiring board 13, and mounts the chip component 18 thereon at another predetermined position on the wiring board 13. Is formed. The wiring board 13 is produced by forming the wiring pattern 16 by Cu etc. on the base substrate 15 as flexible base members, such as polyimide, for example.

The wiring pattern 16 may be fixed on the base substrate 15 by an adhesive layer or directly on the base substrate 15 using a film formation method such as a sputtering method or a roll coating method. Moreover, the wiring board 13 can also be manufactured by forming the wiring pattern 16 by Cu etc. on the board | substrate which is comparatively hard and thick like an epoxy board | substrate.

When the mounting component is mounted on the wiring board 13 using the flexible base member (base substrate 15) as the wiring board 13, a circuit board of a COF (Chip On Film) system is formed. On the other hand, when a mounting component is mounted on a wiring board using a hard base member (space board) as the wiring board 13, a circuit board of a COB (Chip On Board) system is formed.

In Fig. 11, the wiring pattern 16 includes an output terminal 16a formed on one side of the circuit board 3 and an input terminal 16b formed on the side opposite thereto. Moreover, the part in the area | region for mounting the liquid crystal drive IC chip 11 of the wiring pattern 16 comprises the board | substrate side terminal 17. As shown in FIG.

The liquid crystal drive IC chip 11 has a plurality of bumps 14 serving as semiconductor-side terminals on its bonding surface, that is, the active surface. The liquid crystal drive IC chip 11 is mounted at a predetermined position on the base substrate 15 by the anisotropic conductive film 12 as a bonding agent. The chip component 18 is mounted at another predetermined position on the base substrate 15 by soldering. Here, as the chip component 18, a passive component such as a capacitor, a resistor, and an electronic element such as a connector are considered.

As shown in FIG. 12, the anisotropic conductive film 12 is formed by mixing the plurality of conductive particles 21 in the adhesive resin 19. The liquid crystal drive IC chip 11 is fixed to the base substrate 15 by the adhesive resin 19 in the anisotropic conductive film 12, and the bumps 14 of the liquid crystal drive IC chip 11 are anisotropic. The conductive particles 21 in the conductive film 12 are electrically connected to the substrate-side terminal 17 of the wiring pattern 16.

When manufacturing the circuit board 3 shown in FIG. 12, first, the wiring pattern 16 of a predetermined pattern is formed on the base substrate 15, the wiring board 13 is produced, and the anisotropic conductive film 12 is next. The adhesive liquid in the anisotropic conductive film 12 by heat-compressing the liquid crystal driving IC chip 11 in a state where the liquid crystal driving IC chip 11 is positioned at a predetermined position on the wiring board 13 with a gap between them. 19 is used in a molten state, whereby the liquid crystal drive IC chip 11 is mounted on the wiring board 13.

Thereafter, the solder is patterned by printing, dispensing, or the like at the position where the chip component 18 (see FIG. 11) is mounted on the wiring board 13, and the chip component 18 is further placed on the solder pattern. Is placed, the wiring board 13 in that state is inserted into a furnace of a high temperature furnace heated at 200 ° C. to 250 ° C. for a short time to be heated, and is further taken out of the furnace and cooled.

The insertion time at this time is a time as short as possible sufficient to melt the solder. When the above series of processes related to the solder, the so-called solder reflow process, are completed, the chip component 18 is placed at a predetermined position on the wiring board 13 on which the liquid crystal drive IC chip 11 is already mounted. It is in a state of being attached by solder.

Here, the process of attaching the IC chip 11 to the wiring board 13 and the process of attaching the chip component to the wiring board 13 may be reversed. That is, after mounting the chip component 18 to the wiring board 13, the IC chip 11 may be mounted to the wiring board 13.

The circuit board 3 comprised as mentioned above is connected to the protrusion part of the board | substrate 6a of the liquid crystal panel 2 by the anisotropic conductive film 22 in FIG. Like the anisotropic conductive film 12, the anisotropic conductive film 22 is formed of the adhesive resin and the electroconductive particle mixed in it, and as shown in FIG. The board | substrate 6a adheres, and the electroconductive particle connects the output terminal 16a of the circuit board side, and the connection terminal 9 of the board | substrate side to electroconductive connection.

Further, in the circuit board 3, a dummy wiring layer 23A is provided in a region inside the surface of the base substrate 15 on which the liquid crystal driving IC chip 11 is mounted, rather than the substrate-side terminal 17. have. As shown in FIG. 13, the dummy wiring layer 23A is formed of a plurality of independent line segment patterns (a plurality of line segment patterns parallel to the short sides of the IC chip 11) arranged in parallel with each other along one left and right direction. It is. Openings 24 that are open outwardly are formed between the line segment patterns.

Although this dummy wiring layer 23A can be formed independently via a dedicated process, in this embodiment, the substrate-side terminal 17 and the wiring pattern 16 are formed by a conventional patterning method, for example, a photolithography method. In forming, it forms simultaneously with the same material, for example, Cu. In addition, although the surface of the board | substrate side terminal 17 formed by Cu etc. is given Ni plating, Au plating, Sn plating, solder plating, etc., in this case, the surface of the dummy wiring layer 23A is also plated similarly.

In the above plating process, since the dummy wiring layer 23A of the present embodiment is formed by line segment patterns electrically insulated from each other, it is difficult to use the electrolytic plating treatment, and therefore, the dummy wiring layer 23A It is suitable to perform plating process by an electroless plating process.

Since the dummy wiring layer 23A is a structure in which metals such as Cu and the like are plated with Ni or Au plating on the surface thereof, the anisotropic conductive film 12 is compared with the space substrate 15 formed of polyimide or the like. The adhesiveness with respect to the adhesive resin in () is high. Moreover, adhesive force improves also as the dummy wiring layer is provided and the adhesive area of the bonding agent on the space substrate side becomes large. In addition to this, the dummy wiring layer can prevent the intrusion of humidity from the base substrate side and can suppress the decrease in the adhesive strength of the bonding agent due to the change in time. Therefore, when the dummy wiring layer 23A is provided in the region where the liquid crystal drive IC chip 11 is mounted in the base substrate 15, the adhesive force between the anisotropic conductive film 12 and the base substrate 15, that is, the liquid crystal The adhesion between the driving IC chip 11 and the base substrate 15 becomes strong, and as a result, the connection reliability of the liquid crystal driving IC chip 11 to the base substrate 15 is improved.

In addition, since the opening part 24 is formed in the dummy wiring layer 23A, when the anisotropic conductive film 12 is heat-compressed to the base substrate 15, a part of the pressurized anisotropic conductive film 12 is partially opened. It flows out through 24. As a result, the occurrence of residual stress in the anisotropic conductive film 12 can be reduced, and the thickness of the anisotropic conductive film 12 can be made uniform. As a result, the distortion of the base substrate 15 is eliminated and residual stress can also be reduced.

5. <Fifth Embodiment>

The fifth embodiment differs from the fourth embodiment in the shape of the dummy wiring layer. Otherwise, it is comprised similarly to 4th Embodiment, and the description is abbreviate | omitted. In addition, in drawing, each part similar to 4th Embodiment is attached | subjected the same code | symbol as 1st Embodiment.

FIG. 14 is a partial plan view showing the circuit board of the present embodiment as a state before the IC chip 11 for liquid crystal drive is mounted. The dummy wiring layer 23B of the present embodiment is formed by one continuous pattern extending in one direction (that is, left and right directions in the drawing) while meandering. This dummy wiring layer 23B also has an open portion 24 that opens toward the outside. Since the dummy wiring layer 23B has a single connected pattern, an electroplating process can be used when plating the surface.

Also with this dummy wiring layer 23B, the adhesive force between the anisotropic conductive film 12 and the base substrate 15, that is, the adhesive force between the liquid crystal drive IC chip 11 and the base substrate 15 becomes strong, and as a result, the base The reliability of the connection of the liquid crystal drive IC chip 11 to the substrate 15 is improved.

In addition, since the opening part 24 is also formed in the dummy wiring layer 23B, when the anisotropic conductive film 12 is heat-compressed to the base substrate 15, the pressurized anisotropic conductive film 12 flows outward and is anisotropic. The occurrence of residual stress in the conductive film 12 can be reduced, and the thickness of the anisotropic conductive film 12 can be made uniform. As a result, the distortion of the base substrate 15 is eliminated and residual stress can also be reduced.

6. <Sixth Embodiment>

In the sixth embodiment, the shape of the dummy wiring layer is different from that in the fourth embodiment. Otherwise, it is comprised similarly to 4th Embodiment, and the description is abbreviate | omitted. In addition, in drawing, each part similar to 4th Embodiment is attached | subjected the same code | symbol as 1st Embodiment.

FIG. 15 is a partial plan view showing the circuit board of the present embodiment as a state before the IC chip 11 for liquid crystal drive is mounted. The dummy wiring layer 23C of the present embodiment has a plurality of line segment patterns 26 (first line segment regions) arranged in parallel with each other along one direction (that is, the left and right directions in the drawing) and across the line segment pattern 26. It is formed as a continuous pattern by the combination with the linear pattern 27 (2nd line segment area | region) extended in one direction. This dummy wiring layer 23C also has an open portion 24 that opens toward the outside. Since the dummy wiring layer 23C also has a single connected pattern, an electroplating process can be used when plating the surface.

Also with this dummy wiring layer 23C, the adhesive force between the anisotropic conductive film 12 and the base substrate 15, that is, the adhesive force between the liquid crystal drive IC chip 11 and the base substrate 15 becomes strong, and as a result, the base The reliability of the connection of the liquid crystal drive IC chip 11 to the substrate 15 is improved.

In addition, since the opening part 24 is formed also in the dummy wiring layer 23C, when the anisotropic conductive film 12 is heat-compressed with the base substrate 15, the pressurized anisotropic conductive film 12 will flow out and anisotropically. The generation of residual stress in the conductive film 12 can be reduced, and the thickness of the anisotropic conductive film 12 can be made uniform. As a result, the distortion of the base substrate 15 is eliminated and the residual stress thereof can also be reduced.

7. <Modification>

Here, the modification applicable to embodiment mentioned above is demonstrated. In each of the following modifications, only differences from the above-described embodiments will be described.

7.1 In the above-described embodiment, a liquid crystal panel and a simple matrix in which TN-type liquid crystals are encapsulated using a passive matrix type driving method using a thin film diode (TFD), which is a two-terminal switching element, as a liquid crystal panel. The electro-optical characteristic shows the liquid crystal panel which enclosed the liquid crystal of STN (Super Twisted Nematic) type using a drive. However, the liquid crystal panel is not limited to this, and in terms of the driving method, a liquid crystal panel of a static driving type, a three-terminal switching element such as a TFT (Thin Film transistor) or a two-terminal switching element, for example Active-matrix liquid crystal panel using metal-insulator-metal (MIM), electro-optical characteristics, such as guest-host type, phase transition type, ferroelectric type, and memory-stable bistable nema The liquid crystal panel of various forms, such as BTN type using a tick liquid crystal, can be used.

7.2 Further, the flat display panel used in the present invention is not limited to a liquid crystal panel, and other flat display panels, for example, an EL (Electro-Luminescence) display panel, a PDP (Plasma Display Panel) display panel, and a FED (Field) Emission Display) panel or the like.

7.3 Moreover, in each said embodiment, the example in which the semiconductor device as a drive circuit was attached to the circuit board, and the circuit board was connected to the flat display panel was shown. However, the circuit board of the present invention connected to the flat display panel may be a circuit board on which any one of a semiconductor device of a driving circuit, a semiconductor device of an image signal processing circuit, a semiconductor device of another circuit, and the like is mounted.

7.4 Moreover, in each said embodiment, although the case where the circuit board which concerns on this invention is used as a component of a liquid crystal device was shown, the circuit board which concerns on this invention can be used as a component of arbitrary apparatus other than a liquid crystal device. have.

7.5 Thus, in each of the above embodiments, a projector and a mobile phone are shown as examples of electronic devices in which the display device using the circuit board according to the present invention is combined. However, as the electronic apparatus which combined the display apparatus using the circuit board which concerns on this invention, besides these, the liquid crystal television, the viewfinder type monitor direct view type | mold video tape recorder, the car navigation apparatus, the electronic notebook, the electronic calculator, the word And a processor workstation, a mobile phone, a pager, a television phone, a point of sales terminal, and a touch panel.

7.6 The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the present invention or within the equivalent range of the claims.

In a circuit board having a structure in which a semiconductor chip is mounted on a base substrate using a resin for adhesion by use of a display device and an electronic device using the circuit board and the circuit board of the present invention, The adhesion can be improved, the electrical connection reliability of the semiconductor chip and the wiring board can be improved, the degradation of the performance and the reliability of the semiconductor chip can be prevented, and the intrusion of moisture into the bonding region on the base substrate side can be reduced.

Claims (17)

A wiring board having an insulating base member and a plurality of substrate-side terminals provided on the base member; A plurality of semiconductor side terminals, the semiconductor side terminals being electrically connected to the substrate side terminals, and having a semiconductor chip mounted on the wiring board, And the wiring board is provided with a dummy wiring layer insulated from the substrate-side terminal and the semiconductor-side terminal in a region where the semiconductor chip is mounted and in an inner region of the substrate-side terminal. 2. The circuit board according to claim 1, further comprising a resin encapsulation portion for encapsulating a portion in which the semiconductor side terminal and the substrate side terminal are electrically connected, and for bonding the semiconductor chip to the wiring board. The method of claim 2, wherein the resin encapsulation portion is formed by an anisotropic conductive film in which conductive particles are dispersed and mixed in a resin, And the semiconductor side terminal and the substrate side terminal are electrically connected by the conductive particles. The circuit board according to any one of claims 1 to 3, wherein the dummy wiring layer is formed of the same material as the terminal on the substrate side. The circuit board according to any one of claims 2 to 4, wherein the base member is formed of a material having flexibility. The circuit board according to any one of claims 1 to 5, wherein the base member, the dummy wiring layer, and the board side terminal are directly joined without interposing an adhesive layer. The plane according to any one of claims 1 to 6, wherein in a plane, a base member is exposed in contact with the dummy wiring layer, and further has an open portion continuous to an area where a surrounding base member is exposed, And the dummy wiring layer is in planar contact with only the opening. 8. The circuit board according to any one of claims 1 to 7, wherein the dummy wiring layer is formed as a single continuous region. 9. The circuit board of claim 8, wherein the dummy wiring layer is formed as a meandering region. 9. The circuit board according to claim 8, wherein the dummy wiring layer is formed as a region in which a plurality of first line segment regions parallel to each other and a second line segment region extending across the first line segment region are combined. The circuit board according to any one of claims 1 to 6, wherein the dummy wiring layer has one or more openings. The circuit board according to any one of claims 1 to 6, wherein the dummy wiring layer is formed as a plurality of dummy wiring regions spaced by a region where the base member is exposed. The circuit board of claim 12, wherein the plurality of dummy wiring regions are partially connected to each other. The circuit board according to any one of claims 1 to 6, wherein the dummy wiring layer has one or more recesses having a thickness of the wiring layer thinner than that of other regions of the dummy wiring layer. The display device which has a flat panel provided with the circuit board of any one of Claims 1-14, and the connection terminal in which the said circuit board was electrically connected. The liquid crystal panel of claim 15, wherein the flat panel is a liquid crystal panel having a pair of opposing substrates and a liquid crystal encapsulated between the pair of substrates, And the connection terminal is formed on at least one of the pair of substrates. An electronic device having the display device according to claim 15 or 16 as display means.