JP3207743B2 - Terminal structure of flexible wiring board and mounting structure of IC chip using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a terminal structure which is for a flexible wiring board and hardly deformed by heat or stress induced when an IC chip is mounted on the flexible wiring board and a mounting structure enhanced in reliability by the use of the above terminal structure. SOLUTION: An inner lead connection part 6 which serves as a mounting region where a driver IC chip is mounted is provided to a two-layered flexible wiring board 1 by the use of an anisotropic conductive film, inner leads are extended into the lead connection part 6, dummy terminals 11 which are not connected to signal lines are provided to a part of the connection part 6 where inner leads are arranged sparse in wiring pitch so as to make the inner leads uniform in wiring pitch at the connection part 6, whereby the wiring pitch of the inner leads is set at the same reference value on both an input signal side and an output signal side. By this setup, a non-wiring region which makes a flexible wiring board uneven in thermal expansion coefficient and stress generation can be eliminated, so that a mounted product which is hardly deformed and high in reliability can be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal structure of a flexible wiring board suitable for mounting on a display panel using liquid crystal, plasma, or the like, and an IC (Integrated Circuit) using the same.
The present invention relates to a mounting structure of a chip, and particularly to a terminal structure of a flexible wiring board on which an IC chip is mounted using an anisotropic conductive film and a mounting structure of an IC chip using the same.

[0002]

2. Description of the Related Art Conventionally, a driver IC chip used for a liquid crystal panel or the like is mounted on a flexible wiring board (Flexible Printed Circuit Board).
In order to mount on an inted circuit (hereinafter abbreviated as FPC), a technical system such as inner lead bonding or flip chip bonding is employed.

First, the structure of an FPC 50 used for inner lead bonding will be described. As shown in FIG. 3A, a device hole 52 is formed in the center of a substrate 51 made of polyimide (PI). . The formation range of the device hole 52 is determined by the driver IC chip 53
This is a chip mounting area for mounting a chip.

[0004] Strip-shaped copper terminals 55 are arranged on the base material 51 in which the device holes 52 are formed, via an adhesive layer 54 mainly composed of epoxy (EP) resin. At this time, a tip portion of the copper terminal 55 (hereinafter, referred to as an inner lead 55a) extends to the inside of the device hole 52 in preparation for connection with the driver IC chip 53. (Sn) Plating is applied. Further, the peripheral portion of the device hole 52 is covered with a resist 56 in order to protect the copper terminal 55 from deterioration due to oxidation or electrochemical reaction.

As described above, the FPC 50 used for the inner lead bonding is composed of three layers in which the base material 51, the adhesive layer 54, and the copper terminals 55 are laminated.

Next, when the driver IC chip 53 is mounted on the FPC 50, the bumps 57 made of gold (Au) and the inner leads 55a are thermocompression-bonded on the electrodes of the driver IC chip 53. , At the interface
Since the u-Sn alloy is generated, the FPC 50 and the driver IC chip 53 are connected. After connection,
The strength is obtained by sealing the periphery of the driver IC chip 53 and the device hole 52 with the resin 58.

On the other hand, in recent years, an IC chip is connected by flip-chip bonding to a two-layer FPC in which copper terminals are formed on a base material by plating or etching without using an adhesive such as a three-layer FPC. Is being researched and is about to enter the practical stage.

To explain the flip chip bonding method in detail, the structure of the two-layer FPC 60 will be described. As shown in FIG. 3B, polyimide or polyethylene terephthalate (PET), which is less expensive than polyimide, is used.
Alternatively, a chip mounting area 63 for mounting a driver IC chip 62 is set at the center of a base material 61 made of a polyester resin such as polyethylene naphthylate (PEN). The copper terminal 64 is formed so that the (inner lead) extends.

The periphery of the chip mounting area 63 is covered with a resist 65 similar to the resist 56.

Next, when the driver IC chip 62 is mounted on the two-layer FPC 60, an anisotropic conductive film (AC) is formed on the chip mounting area 63.
F) Attach 66, and place the driver IC chip 6
2, and the driver IC chip 62 is subjected to thermocompression bonding. The anisotropic conductive film 66 is formed, for example, by dispersing conductive particles 66 a in an epoxy resin. The conductive pressure is applied between the bump 67 formed on the electrode of the driver IC chip 62 and the copper terminal 64 by thermocompression pressure. The particles 66a are crushed to electrically connect the bump 67 and the copper terminal 64, and the epoxy resin of the anisotropic conductive film 66 is cured by heat of thermocompression bonding. Is fixed while maintaining the typical connection state.

In the case of this method, the epoxy resin of the anisotropic conductive film 66 replaces the resin 58 of FIG. 3A, so that a separate resin sealing step is not required.

Next, the arrangement of the copper terminals 64 provided in the two-layer FPC 60 will be described with reference to the plan view of FIG.

A plurality of input terminals 64a as copper terminals 64 are arranged on one long side of the rectangular two-layer FPC 60, and output terminals 6 as copper terminals 64 are arranged on the other long side.
4b are arranged in plurality. The resist 65 is arranged in a square O-shape around the center of the two-layer FPC 60, and the chip mounting area 63 is set inside the inner peripheral edge 65a.

The wiring of the terminals 64a and 64b is routed using the blank space of the two-layer FPC 60 so that the respective tips of the input terminals 64a and the output terminals 64b reach the chip mounting area 63. Have been.

Further, the input terminals 64a have a wider width than the output terminals 64b in the vicinity of the long side on the input side and are arranged at equal pitches. The width is reduced to the same width as 64b, and in the chip mounting area 63, they are arranged at unequal intervals, that is, in a state where density is generated, so as to match the formation position of the bump 67 of the driver IC chip 62.

On the other hand, the output terminal 64b has the same width,
Alternatively, the bumps 67 are narrowed to the pitch at which the bumps 67 are formed in the driver IC chip 62, reach the four sides of the rectangular chip mounting area 63, and are arranged at regular intervals according to the positions at which the bumps 67 are formed in the driver IC chip 62. Although the wiring is routed, the chip mounting area 6
At the four corners of No. 3, there are blank areas 68 without wiring.

Therefore, it can be said that the copper terminals 64 are unevenly distributed on the base material 61 around the chip mounting area 63.

The above-mentioned FPC 50 and two-layer FPC 60
Is called a TCP (Tape Carrier Package) type, which is a mainstream in packaging mass production technology.

JP-A-6-53275 discloses that TCP is used.
In the system, it is disclosed that a dummy wiring is arranged near a corner of the driver IC chip in order to reduce mechanical stress concentrated around the driver IC chip during inner lead bonding.

[0020]

However, in the conventional terminal structure shown in FIG. 4, in the case of flip chip bonding in which the driver IC chip 62 is thermocompressed by attaching an anisotropic conductive film 66 to the chip mounting area 63. Since the copper terminals 64 having a different coefficient of thermal expansion from the base material 61 are unevenly distributed, 140
The heat required to obtain a connection temperature of
There is a problem that deformation such as warpage or undulation occurs in P. In particular, when the material of the base material 61 is easily affected by heat, such as PET or PEN described above, the thermal deformation becomes remarkable.

In this case, since the two-layer FPC 60 on which the driver IC chip 62 is mounted is deformed, it is difficult to align the two-layer FPC 60 with the liquid crystal panel when connecting to a liquid crystal panel or the like. Furthermore, since stress remains in the two-layer FPC 60 even after the assembly is completed, the copper terminals 6
4 causes a problem of disconnection and a problem that a high reliability required for low-resistance connection between the driver IC chip 62 and the input terminal 64a is reduced.

In the arrangement of the dummy wiring disclosed in Japanese Patent Laid-Open Publication No. 6-53275, the two-layer FPC 60 for liquid crystal is used.
When the number of wires of the input terminal 64a and the number of wires of the output terminal 64b are extremely different from each other as shown in FIG.
The effect of preventing deformation of CP is insufficient. Therefore, particularly when a heat-sensitive substrate such as PET or PEN is used, the problem that wrinkles or disconnections occur during thermocompression bonding cannot be avoided.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to mount an IC chip on an FPC by flip chip bonding.
An object of the present invention is to provide a terminal structure of a flexible wiring board in which a base material of a PC is less likely to be deformed by heat or stress, and to provide a mounting structure with improved reliability using the terminal structure.

[0024]

According to a first aspect of the present invention, there is provided a terminal structure of a flexible wiring board, wherein an IC chip is mounted on the flexible wiring board using an anisotropic conductive film. A dummy terminal that is not connected to a signal line is provided in a portion where the wiring pitch is sparse so that the wiring pitch of the inner lead extending into the mounting region is eliminated. The wiring pitch is set to the same reference value on each of the input signal side and the output signal side.

According to the above arrangement, when mounting an IC chip on a flexible wiring board, an anisotropic conductive film is provided in the mounting area, and after the IC chip is pressure-bonded to the anisotropic conductive film, heat treatment or ultraviolet light is applied. Is applied. At this time, since the density of the wiring pitch of the inner leads extending into the mounting area is eliminated by the dummy terminals on each of the input signal side and the output signal side, variations in the thermal conductivity of the flexible wiring board are reduced on the input signal side. And the output signal side.

Thus, when the anisotropic conductive film is subjected to a heat treatment, it is possible to suppress deformation of the flexible wiring board such as warpage or undulation caused by variation in thermal conductivity. In addition, it is possible to use an inexpensive material that is easily affected by heat, such as PET or PEN, for the base material of the flexible wiring board.

Further, the stress generated by the shrinkage of the thermosetting resin or the ultraviolet curable resin contained in the anisotropic conductive film due to the heat treatment or the ultraviolet irradiation treatment does not cause the wiring pitch of the inner leads to vary, so that the flexible wiring substrate Is uniformly applied to both the input signal side and the output signal side. Thereby, deformation such as warpage or undulation of the flexible wiring board due to curing of the anisotropic conductive film can be suppressed.

Note that an IC for a flexible wiring board
Even when mass mounting the chip by the TCP method, the TCP
No deformation such as warpage or undulation occurs.

As described above, since the deformation of the flexible wiring board is suppressed, the residual stress of the deformation is not applied to the connection portion between the inner lead and the bump of the IC chip and the wiring, so that troubles such as poor connection and disconnection are caused. Occurrence is suppressed, and a highly reliable mounted product can be provided.

When a flexible wiring board on which an IC chip is mounted is mounted on a display panel using liquid crystal, plasma, or the like, since the flexible wiring board is not deformed, mounting alignment is accurate, and the display panel yield rate is improved. And a highly reliable display panel can be provided.

According to a second aspect of the present invention, there is provided a terminal structure of a flexible wiring board for solving the above-mentioned problems. A dummy terminal is provided according to the shape of the non-wiring area so as to fill the non-wiring area generated by the routing.

In the above structure, the wiring pitch of the inner leads may be adjusted by adjusting the wiring of the inner leads to the bump forming position of the IC chip to be mounted and the input / output signals on the flexible wiring board. This is caused by both the wiring of the wires. In a region where the wiring pitch is sparse, a non-wiring region in which no wiring exists naturally occurs.

Therefore, the non-wiring region is filled,
As described in, dummy terminals are provided according to the shape of the non-wiring area so as to eliminate the density of the wiring pitch of the inner leads, that is, the number, length, end shape, etc. of the dummy terminals according to the shape of the non-wiring area By setting (1), there is no non-wiring area that makes the coefficient of thermal expansion and the generation of stress non-uniform from the periphery of the mounting area, so that the effect obtained from the configuration of claim 1 can be further improved.

According to a third aspect of the present invention, there is provided a terminal structure for a flexible wiring board, in order to solve the above-mentioned problem, in addition to the configuration according to the first or second aspect, all the terminals led into the mounting area are provided. Align the inner lead width to the same reference value,
Further, by providing the dummy terminal, the wiring pitch of the inner leads is set to the same reference value on the input signal side and the output signal side.

According to the above construction, the width of all the inner leads is set to the same reference value, and the wiring pitch of the inner leads is set to the same reference value for the entire mounting area. As described above, the coefficient of thermal expansion and the generation of stress during curing of the anisotropic conductive film are more uniform than the case where the wiring pitch of the inner lead is made the same on each of the input signal side and the output signal side. . Therefore, claim 1
Alternatively, the effect obtained from the second configuration can be further improved.

According to a fourth aspect of the present invention, there is provided a terminal structure for a flexible wiring board, in order to solve the above-mentioned problem, in addition to the configuration according to the first, second or third aspect, wherein one input signal line is connected to the non-input signal line. The semiconductor device is characterized in that it is branched into a plurality of wires by using a wiring region, is guided into the mounting region, and has an increased connection area with a bump formed on an IC chip.

According to the above configuration, the IC chip may include an electrode for which a low resistance connection is particularly required. In such a case, if the input signal line corresponding to the electrode is branched into a plurality of lines, a plurality of inner leads and ICs
Since the bumps can be connected to the chip, the connection area can be increased and the connection resistance of one input signal line can be reduced.

Further, as a result of one input signal line being connected at a plurality of locations, high connection reliability can be maintained even if the connection state between the inner lead and the bump is slightly deteriorated due to environmental conditions.

Further, the input signal line branched into a plurality of lines by using the non-wiring region has the same function as a dummy terminal for equalizing the coefficient of thermal expansion and the generation of stress when the anisotropic conductive film is cured. Therefore, in addition to the effect of the configuration according to the first, second, or third aspect, the connection resistance of one input signal line is reduced, the S / N of a signal is improved, and high connection reliability is achieved. Can be maintained.

The mounting structure of the IC chip according to the invention of claim 5 is to solve the above-mentioned problem.
Wherein the inner lead and the bump formed on the IC chip are connected to each other, and the IC chip is mounted on the mounting area.

Therefore, as described above, it is possible to provide an IC chip mounting structure which is highly reliable and has an effect of improving the yield rate of a display panel using liquid crystal, plasma, or the like.

According to a sixth aspect of the present invention, there is provided an IC chip mounting structure, wherein the dummy bumps not connected to the signal lines correspond to the dummy terminals in the IC chip according to the fifth aspect. And the dummy terminals and the dummy bumps are connected to each other.

By connecting the dummy terminals of the flexible wiring board and the dummy bumps of the IC chip according to the above configuration, particularly when the IC chip is thermocompression-bonded to the mounting area of the flexible wiring board using an anisotropic conductive film. And IC
Since the heat applied to the chip is transmitted from the dummy bumps to the dummy terminals and further to the base material of the flexible wiring board, the heat conduction in the flexible wiring board is performed more uniformly than when the dummy bumps are not provided on the IC chip. . This effect is improved as the width and wiring pitch of the inner leads and the dummy terminals are made more uniform in the mounting area, and as the connection area between the dummy terminals and the dummy bumps is made more uniform in the mounting area.

Therefore, the effect obtained by the configuration according to any one of claims 1 to 5 can be further improved.

[0045]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

As shown in FIG. 2, the two-layer FPC 1 as a flexible wiring board is composed of a base material 2 and copper terminals 3 formed on the base material 2 by plating or etching. A large number of two-layer FPCs 1 are continuously formed in tandem by the TCP method for mass production. The substrate 2 is made of polyimide or a polyester resin such as polyethylene terephthalate (PET) or polyethylene naphthylate (PEN), which is less expensive than polyimide.

The terminal arrangement of the copper terminals 3 will be described with reference to the plan view of FIG. The rectangular two-layer FPC 1 is roughly divided into four functional areas. The “first functional area” is the input connection unit 4 set on one long side of the rectangle.
And the input terminals 4a are arranged at equal intervals. The “second functional region” is an output connection portion 5 set on the other long side of the rectangle, and the output terminals 5a narrower than the input terminals 4a are arranged at equal intervals at a wiring pitch smaller than the input terminals 4a. Are located. The input terminal 4a and the output terminal 5a
Constitutes the copper terminal 3 described above.

As described above, the reason why the width of the input terminal 4a in the input connection section 4 is set wider than that of the output terminal 5a is that the resistance to the input signal is suppressed as low as possible.
This is for securing the S / N, and is suitable for use in a liquid crystal display panel or a plasma display panel.

The "third functional area" is an inner lead connecting portion 6 set at the center of the two-layer FPC 1 as shown by a dashed line in FIG. The driver IC chip 7 is mounted. The inner lead connection portion 6 corresponds to a mounting area described in claims. Lastly, the “fourth functional area” is a routing wiring section 8 set between the input connection section 4 and the output connection section 5 and around the inner lead connection section 6. As shown by the two-dot chain line of the frame, the frame is covered with the resist 9.
This resist 9 is provided to protect the copper terminals 3 from deterioration due to oxidation or electrochemical reaction.

Further, the respective tips of the input terminals 4a and the output terminals 5a, which are referred to as inner leads, reach the inner lead connection portions 6 in accordance with the positions where the bumps 10 (see FIG. 2) of the driver IC chip 7 are formed. In addition, the wiring of each terminal 4a, 5a is routed using the routing wiring section 8.

More specifically, the input terminal 4a is narrowed to almost the same width as the output terminal 5a while approaching the inner lead connection portion 6 from the input connection portion 4, and all the inner leads have a rectangular shape. Input connection part 4 of inner lead connection part 6
It is wired so as to be guided to the center of the long side of the side. However, the inner lead of the input terminal 4a is a driver IC
In response to the irregular arrangement of the bumps 10 of the chip 7 due to the restrictions on IC fabrication,
That is, the wirings are arranged in a state where the density is high and low.

On the other hand, the output terminals 5a are wired at equal intervals so that most of the inner leads are linearly led to the long side of the inner lead connection portion 6 on the output connection portion 5 side. However, a part of the output terminal 5a goes around the long side where the inner lead of the input terminal 4a is arranged, and is bent and wired so as to be guided near both ends of the inner lead of the input terminal 4a. The wiring is bent so as to be guided to both short sides of the inner lead connection portion 6.

As described above, the input terminal 4a and the output terminal 5a reach the inner lead connection portion 6 in accordance with the position where the bump 10 of the driver IC chip 7 is formed.
As a result of the wiring, a non-wiring area, which is conventionally left as a blank area, occurs in a portion where the inner leads of the input terminal 4a are sparsely arranged and in the vicinity of the four corners of the inner lead connecting portion 6.

Therefore, according to the present invention, the dummy terminal 11 (which is not connected to either the input terminal 4a or the output terminal 5a) and is in a floating state is connected to all but a part of the non-wiring region. (Indicated by hatching). These dummy terminals 11 are provided at the same pitch as the wiring interval (wiring pitch) between adjacent input terminals 4a and output terminals 5a in at least the inner lead connection portion 6 in each non-wiring region. Further, from the viewpoint of making the coefficient of thermal expansion of the base material 2 uniform in the thermocompression bonding step of flip chip bonding, each non-wiring region has a dummy number, length and end shape corresponding to the shape of the non-wiring region. It is desirable to provide the terminal 11.

Further, in a part of the non-wiring region excluded from the above description, when the input terminal 4a to be connected to the bump 10 which is particularly required to have low resistance connection is arranged.
As shown by a branch input terminal 4b in FIG. 1, the input terminal 4a uses a non-wiring area in the middle of the wiring to branch into a plurality of wires having the same width as the inner lead of the other input terminal 4a and the dummy terminal 11. And is led to the inner lead connection portion 6.

It should be noted that being the same in the wiring pitch and the terminal width means that the same reference value is used in the manufacturing process of the terminals 4a, 4b, 5a and 11; It goes without saying that a certain error range is involved.

In the above configuration, the non-wiring area, which was conventionally left as a blank area, is filled with the dummy terminals 11 provided at the same wiring pitch as the inner leads of the terminals 4a and 5a. It is filled with a plurality of branched input terminals 4b using the wiring area at the same wiring pitch as the inner leads.

Therefore, the two-layer FPC 1 according to the present invention
Has a terminal structure as if the wiring was made in a uniform manner without unevenness over the entire inner periphery and outer periphery of the inner lead connection portion 6.

As a result, as shown in FIG. 2, the anisotropic conductive film 12 is adhered to the inner lead connection portion 6 by flip chip bonding, and the driver IC chip 7 is disposed thereon and subjected to thermocompression treatment. Is performed, the coefficient of thermal expansion around the inner lead connection portion 6 is uniform,
There is no uneven thermal expansion of the substrate 2. Therefore, deformation such as warpage or undulation does not occur in the two-layer FPC 1 itself or the two-layer FPC 1 formed in tandem by the TCP method. This also makes it possible to use an inexpensive material that is easily affected by heat, such as PET or PEN, for the substrate 2.

Further, since no deformation occurs in the two-layer FPC 1, the two-layer FPC 1 and the driver IC chip 7 can be accurately and easily aligned with each other, and the yield of assembled products can be improved. Further, since the two-layer FPC 1 on which the driver IC chip 7 is mounted is not deformed, the alignment between the assembled product of the two-layer FPC 1 and the liquid crystal panel becomes easy when connecting to the liquid crystal panel or the like. Furthermore, since no deformation stress remains in the two-layer FPC 1 after assembly,
The problem that the copper terminal 3 is disconnected can be solved, and the high reliability required for the low resistance connection between the driver IC chip 7 and the input terminal 4a can be maintained.

Furthermore, a plurality of branch input terminals 4b are provided for the bumps 10 ', which require a particularly high degree of low-resistance connection, so that the connection state between the branch input terminals 4b and the bumps 10' depends on environmental conditions. , Even if is slightly degraded, it is possible to keep maintaining high connection reliability.

In this embodiment, the case where all of the inner leads of the input terminals 4a and 4b, the inner leads of the output terminal 5a, and the dummy terminals 11 are arranged at equal intervals around the inner lead connecting portion 6 will be described. However, the present invention is not limited to this. For example, when the width of the inner lead is different between the input terminals 4a and 4b and the output terminal 5a, the input terminals 4a and 4b
b and the dummy terminals 11 are arranged at equal intervals at a first wiring pitch, and the inner leads of the output terminals 5a and the dummy terminals 11 are equally spaced at a second wiring pitch different from the first wiring pitch. It may be arranged in.

That is, what is common in any case is that the pitch of the dummy terminal 11 and the branch input terminal 4b in the non-wiring area is set to be as close as possible to the pitch of the surrounding wiring. is there. By doing so, the non-wiring area is left as a blank area,
A high effect of preventing the deformation of the layer FPC1 can be obtained.

Next, a method of providing the bumps 10 formed on the electrodes of the driver IC chip 7 will be described with reference to FIG. FIG. 2 shows a cross section taken along line AA ′ of FIG. The driver IC chip 7 is provided with a plurality of bumps 10 corresponding to the input terminals 4a, and further provided with dummy bumps 13 corresponding to the dummy terminals 11. Also, the bumps 10 ′ having a large area are provided on the electrodes of the driver IC chip 7, which are particularly required for low resistance connection.
Are formed, and the bump 10 'and the branch input terminal 4b branched into a plurality of bumps are arranged so as to face each other.

The anisotropic conductive film 12 is formed by dispersing conductive particles 12a in, for example, epoxy resin. During flip chip bonding, the pressure between the bump 10 and the input terminal 4a, the bump 10 ' The conductive particles 12 a are crushed between the dummy terminal 13 and the dummy input terminal 4 b and between the dummy bump 13 and the dummy terminal 11. As a result, the bumps 10 are electrically connected to the input terminals 4a and the bumps 10 'and the branch input terminals 4b, and the dummy bumps 13 and the dummy terminals 11 are connected so that heat is transmitted to each other. Further, the anisotropic conductive film 12 is formed by the heat of thermocompression bonding.
The above connection is fixed and held because the epoxy resin is hardened.

Note that, instead of the anisotropic conductive film 12, an anisotropic conductive film in which conductive particles are dispersed in a photocurable resin which is cured by irradiation with light such as ultraviolet rays may be used.

As described above, it is desirable that the bumps 10 are completely arranged at regular intervals. However, as described above, when it is difficult to arrange the bumps 10 at regular intervals due to restrictions on IC fabrication, the bumps 10 correspond to the dummy terminals 11. Since the dummy bumps 13 are provided, heat conduction in the non-wiring region becomes uniform. Thereby, the coefficient of thermal expansion of the substrate 2 can be made more uniform. Further, by connecting the dummy terminals 11 and the dummy bumps 13, the pressure applied to the base material 2 becomes uniform as a whole, so that the connection reliability can be improved.

The bumps 10 and 10 ′ are connected so that the connection areas between the bumps 10 and 10 ′ and the dummy bumps 13 and the terminals 4 a, 4 b, 5 a, and 11 are all the same and are connected at equal intervals. By providing the dummy bumps 13, the heat conduction becomes uniform around the inner lead connection portion 6, so that the coefficient of thermal expansion of the base material 2 is further uniformed,
Deformation can be reliably prevented.

In this embodiment, the case where the wiring pitch in the inner lead connection portion 6 is set to be the same is shown. However, even if there is a certain difference in the wiring pitch, the non-wiring The respective effects described above are achieved as compared with the case where the blank area is left as it is. However, if the wide wiring pitch is twice or more as large as the narrow wiring pitch, stress due to heat and pressure during bonding is unevenly applied to the two-layer FPC1, so that distortion occurs. Further, in this case, a portion where stress is concentrated due to a mechanical force applied from the outside is likely to be generated, and it is easy to cause disconnection in the routing wiring portion 8.

[0070]

According to the terminal structure of the flexible wiring board according to the first aspect of the present invention, as described above, the flexible wiring board is provided with a mounting area for mounting an IC chip using an anisotropic conductive film. A dummy terminal that is not connected to a signal line is provided in a part where the wiring pitch is sparse so as to eliminate the sparseness of the wiring pitch of the inner lead extending into the region,
The wiring pitch is set to the same reference value on each of the input signal side and the output signal side.

Therefore, since the density of the wiring pitch of the inner leads is eliminated by the dummy terminals on each of the input signal side and the output signal side, the variation in the thermal conductivity of the flexible wiring board is reduced on each of the input and output signal sides. Can be smaller. Thereby, when the heat treatment is performed on the anisotropic conductive film, it is possible to suppress deformation of the flexible wiring board such as warpage or undulation due to variation in thermal conductivity.

Further, since the stress generated by the contraction of the thermosetting resin or the photocurable resin contained in the anisotropic conductive film is uniformly applied to each of the input signal side and the output signal side of the flexible wiring board, It is possible to suppress deformation such as warpage or undulation of the flexible wiring board due to curing of the conductive conductive film.

As a result, (1) deformation such as warpage or undulation does not occur in the mass-produced TCP, and (2) troubles such as poor connection or disconnection occur in a mounted product in which an IC chip is mounted on a flexible wiring board. Various advantages are also obtained, namely: (3) it is possible to improve the non-defective rate of a display panel such as a liquid crystal in which a mounted product is assembled, and (4) it is possible to provide a highly reliable display panel.

As described above, the terminal structure of the flexible wiring board according to the second aspect of the present invention is generated by the wiring of the input signal lines or the output signal lines having the inner leads as the end portions. In this configuration, dummy terminals are provided in accordance with the shape of the non-wiring region so as to fill the non-wiring region.

Therefore, by providing dummy terminals in accordance with the shape of the non-wiring region which naturally occurs in the region where the wiring pitch is sparse, the dummy terminals are provided so as to eliminate the sparseness of the wiring pitch of the inner leads, thereby allowing thermal expansion from the periphery of the mounting region. Since there is no non-wiring region that makes the rate and stress generation non-uniform, the effect of the configuration of claim 1 can be further improved.

According to a third aspect of the present invention, as described above, in addition to the configuration of the first or second aspect, the width of all the inner leads led into the mounting area is provided. Are arranged to the same reference value, and the dummy terminals are provided, so that the wiring pitch of the inner leads is adjusted to the same reference value on the input signal side and the output signal side.

Therefore, the widths of all the inner leads are set to the same reference value, and the wiring pitch of the inner leads is set to the same reference value for the entire mounting area. Since the stress generation during the curing of the conductive film is made more uniform, the effect of the configuration of claim 1 or 2 can be further improved.

The terminal structure of the flexible wiring board according to the fourth aspect of the present invention is as described above.
In addition to the configuration described in 1 above, one input signal line is branched into a plurality of lines by using the non-wiring region, guided into the mounting region, and the connection area with the bump formed on the IC chip is increased. Configuration.

Therefore, when the IC chip includes an electrode for which low resistance connection is particularly required, if the input signal line corresponding to the electrode is branched into a plurality of lines, the connection with the bump of the IC chip can be made. The area can be increased, and the connection resistance of one input signal line can be reduced. Also, even if the connection state between the inner lead and the bump is slightly deteriorated due to environmental conditions as a result of one input signal line being connected at a plurality of locations,
High connection reliability can be maintained. further,
The input signal lines branched into a plurality of lines by using the non-wiring region have the same function as the dummy terminals, and therefore, are set forth in claim 1,
In addition to the effects of the configuration described in 2 or 3, the connection resistance of one input signal line can be reduced, the signal S / N can be improved, and the connection reliability can be maintained for a long time. This has the effect.

The mounting structure of an IC chip according to a fifth aspect of the present invention connects the inner lead according to any one of the first to fourth aspects and the bump formed on the IC chip as described above. Then, an IC chip is mounted on the mounting area.

Therefore, there is an effect that it is possible to provide a mounting structure of an IC chip which has high reliability and can improve the yield rate of a display panel using liquid crystal or plasma.

According to the mounting structure of the IC chip according to the invention of claim 6, as described above, the IC chip according to claim 5 is provided with dummy bumps not connected to signal lines, corresponding to the dummy terminals, In this configuration, the dummy terminals and the dummy bumps are connected to each other.

Therefore, particularly when the IC chip is thermocompression-bonded to the mounting region of the flexible wiring board by using the anisotropic conductive film, the heat applied to the IC chip is transmitted from the dummy bump to the dummy terminal, and the flexible terminal is further flexible. Since the heat is transmitted to the base material of the wiring board, the heat conduction in the flexible wiring board is performed more uniformly as compared with the case where no dummy bump is provided on the IC chip. This effect is improved as the width and wiring pitch of the inner leads and the dummy terminals are made more uniform in the mounting area, and as the connection area between the dummy terminals and the dummy bumps is made more uniform in the mounting area. Therefore, the effect of the configuration according to any one of claims 1 to 5 can be further improved.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a planar configuration example of a terminal arrangement of a flexible wiring board according to the present invention.

FIG. 2 is a schematic view showing a cross section taken along line AA ′ of FIG. 1;

3A is a cross-sectional view showing a three-layer flexible wiring board on which an IC chip is mounted by conventional inner lead bonding, and FIG. 3B is a cross-sectional view showing an IC chip mounted by conventional flip chip bonding; FIG. 5 is a cross-sectional view illustrating a flexible wiring board having a two-layer configuration, and is a cross-sectional view taken along line XX ′ of FIG. 4.

FIG. 4 is a plan view illustrating an example of a configuration of a conventional terminal arrangement of a flexible wiring board.

[Description of Signs] 1 2-layer FPC (flexible wiring board) 3 Copper terminal (input signal line and output signal line) 4a Input terminal (input signal line) 4b Branch input terminal 5a Output terminal (output signal line) 6 Inner lead connection Part (mounting area) 7 Driver IC chip 10 Bump 10 'Bump 11 Dummy terminal 12 Anisotropic conductive film 12a Conductive particle 13 Dummy bump

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FI H01L 23/50 H01L 23/50 Y (58) Investigated field (Int.Cl. ⁷ , DB name) H01L 23/12 H01L 21 / 52 H01L 21/60 311 H01L 23/50

Claims (6)

(57) [Claims] A flexible wiring board is provided with a mounting area for mounting an IC chip using an anisotropic conductive film, and the wiring pitch of inner leads extending into the mounting area is reduced so that the wiring pitch does not vary. A terminal structure of a flexible wiring board, wherein dummy terminals not connected to signal lines are provided in sparse portions of the wiring lines, and the wiring pitch is set to the same reference value on each of the input signal side and the output signal side. 2. A dummy terminal according to the shape of a non-wiring region so as to fill a non-wiring region generated by routing of input signal lines or output signal lines having the inner lead as a tip. The terminal structure of a flexible wiring board according to claim 1, wherein: 3. The wiring width of the inner leads is adjusted between the input signal side and the output signal side by setting the widths of all the inner leads led into the mounting area to the same reference value and providing the dummy terminals. 3. The terminal structure of a flexible wiring board according to claim 1, wherein the same reference value is set. 4. The method according to claim 1, wherein one input signal line is branched into a plurality of lines by using said non-wiring region, and is guided into said mounting region to increase a connection area with a bump formed on an IC chip. The terminal structure of a flexible wiring board according to claim 1, 2 or 3. 5. An IC wherein the inner lead according to claim 1 is connected to a bump formed on an IC chip, and the IC chip is mounted on the mounting area. Chip mounting structure. 6. The IC chip according to claim 5, wherein a dummy bump not connected to a signal line is provided on the IC chip in correspondence with the dummy terminal, and the dummy terminal and the dummy bump are connected to each other. IC chip mounting structure.