JPH05142555A - Liquid crystal display unit and formation of electrode projection - Google Patents

Abstract

PURPOSE:To assure connection with a smaller number of processes by forming projections on the electrode surfaces of a flexible substrate or a tab for driving and applying an adhesive on the electrode surfaces to be connected, thereby joining the projections to the transparent electrodes of a liquid crystal panel substrate. CONSTITUTION:The plural projections 15 are formed in the positions corresponding to the plating layer of the electrodes 12 on the flexible substrate 11 surface by pressing with a press mold. The adhesive substrate 16 is thereafter applied by means, such as printing, on the electrode terminal surface of the flexible substrate 11 formed with the projections 15. The projections 15 are formed on the electrode 12 surfaces in such a manner and further the juncture of the flexible substrate 11 coated with the adhesive 16 and the electrode terminals of the transparent electrodes of the liquid crystal panel substrate are thermcompression bonded. Then, the electrical connection of the projections 15 formed on the electrodes 12 of the flexible substrate 11 with the electrode terminals of the transparent electrodes is then obtd. while expelling the adhesive 16 thinly covering then surfaces of the projections 15 when the projections are brought into pressurized contact with the electrode terminals of the transparent electrodes of the liquid crystal panel substrate. The physical connection of both electrodes is also obtd. by curing of the adhesive material 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a flexible connection board for connecting a liquid crystal panel substrate made of a flexible film and a drive circuit board, or a connecting portion of a driving TAB directly connected to the liquid crystal panel board. The present invention relates to a method for forming a projection provided on a liquid crystal display unit and a connecting portion.

[0002]

2. Description of the Related Art Conventionally, in a liquid crystal display element formed by bonding a pair of liquid crystal panel substrates with a slight gap therebetween and filling the gaps with liquid crystal, transparent electrode terminals 2 formed on the liquid crystal panel substrate 1 are used. When connecting the wiring terminals 4 of the drive circuit board 3, as shown in FIG. 7, a flexible connection board 5 having wiring electrodes 6 is interposed. Then, between one electrode terminal 6a of the wiring electrode 6 of the flexible connection substrate 5 and the transparent electrode terminal 2 of the liquid crystal panel substrate 1,
Between the other electrode terminal 6b of the wiring electrode 6 and the wiring terminal 4 of the drive circuit board 3, respectively, anisotropic conductive connectors 7a and 7b are provided.
Are connected with.

A case where a TAB 8 is used as a driving IC is shown in FIG. 8, in which one electrode terminal 6a of the wiring electrode 6 of the flexible connection substrate 5 is connected to the transparent electrode terminal 2 of the liquid crystal panel substrate 1. Then, the other electrode terminal 6b of the wiring electrode 6 is connected to the output electrode terminal of the TAB 8, and the anisotropic conductive connectors 7a and 7c are interposed therebetween. TA
B8 and the printed circuit board 9 on which the bus line and the power supply line are arranged are connected by soldering 10.

As described above, in the liquid crystal display unit, many anisotropic conductive connectors are used to connect the electrode terminals because the transparent electrodes (ITO) formed on the liquid crystal panel substrate are solder wettable. Is bad, I can not solder,
Also, liquid crystal panel substrates such as polymer films cannot withstand soldering temperatures, liquid crystal panel substrates with a large display capacity have a narrow electrode pitch of 0.4 mm or less, liquid crystal panel substrates, drive circuit substrates or flexible connection substrates. The surface condition of each of the electrodes is flat, and the reliability is low only by bringing the electrodes into close contact with each other.

By the way, if an anisotropic conductive connector is used at the connecting portion between the electrode terminals of the liquid crystal panel substrate and the electrode terminals of the flexible connection substrate and the drive circuit substrate, the number of steps required for the connection increases. That is, first, the anisotropic conductive connector is cut into a predetermined length, and then temporary compression of the anisotropic conductive connector is applied to one electrode terminal of the flexible connection board and anisotropic conductivity is applied to the other electrode terminal of the flexible connection board. Temporary crimping of connector, separation of one anisotropic conductive connector separator of flexible connection board, connection of liquid crystal panel substrate and flexible connection board, separation of other anisotropic conductive connector separator of flexible connection board, drive circuit Each step of connecting the board and the flexible connection board is required.

Further, the price of the anisotropic conductive connector is high, and the conductive particles in the anisotropic conductive connector are soldered to the electrode terminals of the liquid crystal panel substrate, the flexible connection substrate and the drive circuit substrate. Since it does not form an alloy like the above and conducts electricity by point contact or surface contact with the surface of each electrode terminal, the reliability may deteriorate due to the adhesive, expansion and contraction of each substrate, deformation, etc. It also has drawbacks.

[0007]

SUMMARY OF THE INVENTION The present invention has a small number of steps for connecting an electrode terminal in a liquid crystal panel substrate and a flexible connection substrate or a driving TAB without using an expensive anisotropic conductive connector. An object of the present invention is to provide a liquid crystal display unit provided with a connection portion with high connection reliability.

[0008]

In order to achieve the above object, the present invention uses a flexible film as a liquid crystal panel substrate,
In a liquid crystal display unit using a flexible connection substrate when connecting transparent electrode terminals formed on the liquid crystal panel substrate and wiring terminals formed on a drive circuit substrate, a projection is formed on the electrode connection terminal surface of the flexible connection substrate. In addition, an insulating adhesive is applied to the surface of either one of the electrode terminals connected to the flexible connection board and the liquid crystal panel board or the drive circuit board for connection.

According to the present invention, in the liquid crystal display unit, the flexible connection board connected to the liquid crystal panel board and the drive circuit board has one or more electrodes than the electrodes formed on the liquid crystal panel board and the drive circuit board. It is characterized in that the electrodes are provided, and the arrangement of the protrusions formed on the surface of the electrode connection terminal of the flexible connection substrate is different between the adjacent electrodes.

Further, the present invention provides a liquid crystal display unit comprising a flexible film as a liquid crystal panel substrate, and a transparent electrode terminal formed on the liquid crystal panel substrate and an electrode terminal of a driving TAB are connected to each other. Characterized in that a protrusion is formed on the surface of the electrode terminal of the driving TAB, and an insulating adhesive is adhered to the surface of either one of the electrode terminals where the driving TAB and the liquid crystal panel substrate are connected. Is.

The present invention includes the step of forming the protrusion in the step of forming the flexible connection board or the electrode terminal of the driving TAB, and is formed by this step, or the flexible connection board. Alternatively, it is formed simultaneously with the cutting during the step of cutting the driving TAB into individual pieces.

[0012]

According to the structure of the present invention, when connecting the liquid crystal panel substrate and the flexible substrate or the driving TAB, a protrusion is provided on the electrode surface of the flexible substrate or the driving TAB, and an adhesive is applied to one of the electrode surfaces to be connected. Since coating and bonding are performed, the number of steps is smaller than that in the case of bonding using a conventional anisotropically conductive connector, and the protrusions chemically formed on the electrode surface of the flexible substrate or the driving TAB are formed on the liquid crystal panel substrate. It is possible to obtain a highly reliable and low connection resistance for the transparent electrode.

In the present invention, since the number of electrodes of the flexible substrate is larger than that of the liquid crystal panel substrate and the protrusions formed on the adjacent electrodes are displaced from each other, the repair process has no scratches. The projections of the electrodes of the flexible substrate come into contact with the electrodes of the liquid crystal panel substrate to obtain conduction.

[0014]

[Example] When a conventional anisotropically conductive connector is used for connection of electrode terminals in a liquid crystal display unit, electrical connection is made by conductive particles contained in the anisotropically conductive connector, and a physical adhesive is also used. However, in the present invention, a protrusion is formed on one surface of the electrode terminals to which the electrical connection is joined, and an insulating adhesive is applied as the physical connection. And

Embodiments of the present invention will be described below with reference to the drawings. A flexible substrate provided between the liquid crystal panel substrate and the drive circuit substrate or the liquid crystal panel substrate and the TAB shown in FIG. 7 or FIG. This will be described with reference to FIG. The flexible substrate 11 is made of a material such as polyimide or polyester.
The surface of the electrode 1 is made of a copper material having a thickness of 9 to 35 μm.
2 are configured. This is a known configuration.

In the present invention, the surface of the electrode 12 is plated with gold or solder to prevent oxidation. The thickness of this 13-layer plating is about 3 μm. Then, in order to form protrusions for electrode connection on the surface of the plating layer 13, a press die 14 made of stainless steel, which is harder than the hardness of the electrode 12, and having a concavo-convex portion 14a formed on the surface of the electrode 12, Press. Therefore, as shown in FIG. 2, a plurality of protrusions 1 are formed at a position corresponding to the plating layer 13 of the electrode 12 by pressing the press die 14.
5 is formed.

After that, an adhesive 16 is applied to the surface of the electrode terminal of the flexible substrate 11 having the projections 15 formed on the surface of the electrode 12 by means of printing or the like as shown in the figure. The coating thickness of the adhesive 16 is the electrode 12 of the flexible substrate 11.
In the case of a copper electrode having a thickness of 35 μm, a good adhesion was obtained by setting the coating thickness of 20 to 30 μm so as to cover the protrusion 15 thinly, although it depends on the thickness of the electrode.

As described above, the projection 1 is formed on the surface of the electrode 12.
When the connection portion of the flexible substrate 11 on which 5 is formed and further the adhesive 16 is applied and the electrode terminal of the transparent electrode 2 of the liquid crystal panel substrate 1 of FIG.
The protrusions 15 formed on the electrodes 12 of the liquid crystal panel substrate 1
It is possible to obtain an electrical connection with the electrode terminal of the transparent electrode 2 while removing the adhesive 16 thinly coated on the protrusion 15 when being pressed against the electrode terminal of the transparent electrode 2. Then, the adhesive 16 disposed between the electrodes 12 and 2 is cured, whereby a physical connection is obtained.

In the present invention, the liquid crystal panel substrate is formed by using the projection 15 formed on the surface of the electrode 12 of the flexible substrate 11 and the adhesive 16 applied on the surface of the electrode 12 without using an anisotropic conductive connector. Alternatively, the drive circuit board can be connected to or.

Further, the protrusion 15 formed of the plating layer 13 provided on the surface of the electrode 12 of the flexible substrate 11 is
The adhesiveness with the electrode material copper of the flexible substrate 11 is much more reliable than in the case of the conventional anisotropically conductive connector, and the connection resistance is lower than that of the anisotropically conductive connector. There is an advantage that

As means for forming a protrusion on the surface of the electrode 12 of the flexible substrate 11, other than the above example, a method of selectively plating by masking the electrode, forming the electrode by etching, and then again forming the protrusion by etching. It is possible to use a forming method, a method of masking electrodes and selectively forming vapor deposition, a method of forming protrusions by spattering, or the like, and no special step is required.

Generally, the flexible substrate is 200 m
It is used after being cut from a sheet to a predetermined size in the size of m square. By forming the projections on the electrode surface of the flexible substrate at the same time as this cutting step, a step for forming the projections is not required. In addition, when the drive TAB wound on the reel is cut and used as needed, a protrusion is formed on the electrode surface at the same time, so that no special process is required.

4 to 5 show means for forming projections on the electrode surface at the same time as the cutting step when a punching die is used as a cutting tool for cutting a long drive TAB wound on a reel. This will be described with reference to FIG.
FIG. 4 shows the positional relationship between the upper die 17 and the lower die 18 which are cutting tools and the drive TAB 19 before cutting.
Evacuation recesses 17a and 18a are formed in the IC 8 so that the IC chip 19a of the driving TAB is not loaded.

As is clear from FIG. 5, which is an enlarged view of the portion A in FIG. 4, the upper die 17 has a cutting blade portion 17b between the lower die and the cutting blade portion 17b.
The clearance is set to be not more than μm, and a protrusion forming portion 17c for forming a protrusion on the surface of the electrode 19c is provided in the vicinity of the upper cutting blade portion 17b.
Therefore, when the lower die 18 is placed on the base film 19b of the driving TAB in this state and the upper die 17 is pushed down, first, the blade portion 17b of the upper die 17 cuts the base film 19b, and the upper die 17 is further cut. When pushed down, the protrusion forming portion 17c of the upper mold 17 is pressed against the electrode 19c of the driving TAB to press the electrode 19c, and a protrusion is formed on the surface of the electrode 19c. 19d is a resist film.

As another embodiment of the upper die, as shown in FIG. 6, the upper die 20 has two blocks, a blade portion 20a and a projection forming portion 20b supported by a spring 20c between the blade portions 20a. It consists of a combination. In addition, the blade portion and the protrusion forming portion may be formed in different molds.

The protrusions formed on the electrode surface of the flexible substrate have a wide electrode pitch (≧ 0.5 m).
A conductive paste or the like may be formed in m) by means such as printing or potting. Even if the electrode pitch is narrow, it is possible to form protrusions by the same means,
When the conductive paste flows out from the electrode surface, it may cause a short circuit between adjacent electrodes.
It is necessary to select printing / potting conditions carefully.

When a polymer film is used as the material of the liquid crystal panel substrate, after connecting the electrode connecting portions, if it is judged that the connection is defective in the inspection step, the electrode connecting portions are peeled off and the reconnecting step is performed. There is a drawback in that, when shifting to, the part of the transparent electrode surface on the liquid crystal panel substrate side, which is in contact with the conductive particles by the conventional anisotropic conductive connector, is destroyed. In this respect, even in the case of the present invention which does not use the anisotropic conductive connector, the protrusion of the electrode surface of the flexible substrate causes a part of the transparent electrode surface on the liquid crystal panel substrate side to be destroyed. According to the invention, the broken transparent electrode surface is not connected to the projection on the electrode surface of the flexible substrate during reconnection as described below.

That is, in the present invention, the number of electrodes on the flexible substrate is set to be larger than the number of electrodes originally required, and further,
The projections 15a ₁ and 15a ₂ and the projections 15b ₁ and 15b ₂ formed on the surfaces of the adjacent electrodes 12a, 12b and 12c are arranged differently as shown in FIG. By connecting the transparent electrode on the liquid crystal panel substrate side to the transparent electrode on the liquid crystal panel substrate side by shifting one electrode, the defective connection due to the breakage of the transparent electrode on the liquid crystal panel substrate side is eliminated.

After the protrusion of the electrode of the flexible substrate and the transparent electrode on the liquid crystal panel substrate side once contact, they are separated for reconnection, and even if the contacted transparent electrode portion on the liquid crystal panel substrate side is destroyed, the repair step After that, since the electrodes of the adjacent flexible substrate with different positions of the protrusions correspond to the transparent electrodes, the protrusions of the electrodes of the flexible substrate always contact the surface of the transparent electrode that has not been destroyed, and ensure the Continuity can be obtained.

In the above embodiments, the connection between the liquid crystal panel substrate and the flexible substrate has been described. However, when the driving TAB as shown in FIG. 5 is directly connected to the liquid crystal panel substrate, the electrode surface of the driving TAB is directly connected. It is possible to form a similar protrusion, and then apply an adhesive to the surface of the electrode to connect it to the transparent electrode terminal of the liquid crystal panel substrate. In this case as well, when an anisotropic conductive connector is used, In comparison, a reliable connection can be obtained and a much lower connection resistance can be obtained.

[0031]

According to the structure of the present invention, a protrusion is formed on the electrode surface of a flexible substrate or a driving TAB, and an adhesive is applied to the electrode surface to be connected to bond the transparent electrode of the liquid crystal panel substrate. The number of steps is smaller than that in the case of joining using a conventional anisotropically conductive connector, and the protrusion chemically formed on the electrode surface of the flexible substrate or the driving TAB is reliable for the transparent electrode of the liquid crystal panel substrate. It has the effect of being able to obtain a high connection resistance and low connection resistance, and further, in the repair connection, since the positions of the protrusions are different on the adjacent electrode surfaces, there is no scratch on the transparent electrode of the separated liquid crystal panel substrate. The part and the protrusion are connected,
It has the effect of enabling reliable connection.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a state before forming a protrusion on an electrode surface of a flexible substrate, which is an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a flexible substrate in which protrusions are formed on the electrode surface in FIG. 1, and a state in which an adhesive is applied to the electrode portion of the flexible substrate.

FIG. 3 is an explanatory view showing that the positions of the protrusions formed on the electrode surface of the flexible substrate of the present invention are different between the adjacent electrodes.

FIG. 4 is a schematic view of a configuration in which a projection formed on an electrode surface of a driving TAB is formed at the same time as cutting.

5 is an enlarged view of part A in FIG.

FIG. 6 is a schematic cross-sectional view showing another embodiment of the upper die provided with a blade portion and a protrusion forming portion.

FIG. 7 is a schematic side view showing a state in which a panel substrate and a drive circuit substrate are connected by a flexible substrate using a conventional anisotropic conductive connector.

FIG. 8 is a schematic side view showing a state in which a panel substrate and a driving TAB are connected by a flexible substrate using a conventional anisotropically conductive connector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal panel substrate 2 Transparent electrode terminal 3 Drive circuit board 4 Wiring terminal 8 TAB 9 Printed circuit board 10 Soldering 11 Flexible substrate 12 Electrode formed on flexible substrate 13 Plating layer 14 Press mold 14a Concavo-convex portion 15 Protrusion 16 Adhesive

Front Page Continuation (72) Inventor Masanori Itagaki 1-3-6 Nakamagome, Ota-ku, Tokyo Within Ricoh Co., Ltd. (72) In-house Hisao Takahashi 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Hiroshi Fujimura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) In-house Hiroyuki Sakayose 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (5)

[Claims] 1. A flexible film as a liquid crystal panel substrate,
In a liquid crystal display unit using a flexible connection substrate when connecting transparent electrode terminals formed on the liquid crystal panel substrate and wiring terminals formed on a drive circuit substrate, a projection is formed on the electrode connection terminal surface of the flexible connection substrate. A liquid crystal display unit, characterized in that an insulating adhesive is applied to the surface of either one of the electrode terminals connected to the flexible connection board and the liquid crystal panel board or the drive circuit board for connection. 2. The flexible connection board connected to the liquid crystal panel board and the drive circuit board includes one or more electrodes more than the number of electrodes formed on the liquid crystal panel board and the drive circuit board, and the electrodes of the flexible connection board. The liquid crystal display unit according to claim 1, wherein the arrangement of the protrusions formed on the surface of the connection terminal is different between adjacent electrodes. 3. A flexible film as a liquid crystal panel substrate,
A transparent electrode terminal and a driving T formed on the liquid crystal panel substrate.
In a liquid crystal display unit formed by connecting the electrode terminals of AB, a protrusion is formed on the surface of the electrode terminals of the driving TAB, and the surface of one of the electrode terminals connected to the driving TAB and the liquid crystal panel substrate is formed. A liquid crystal display unit, characterized in that an insulating adhesive is adhered for connection. 4. A flexible connection substrate connected to a liquid crystal panel substrate, or a protrusion formed on a surface of an electrode terminal of a driving TAB is a flexible connection substrate or a driving TA.
A method of forming an electrode projection, characterized in that the step of forming a projection is included in the step of forming the electrode terminal B, and the step is provided by this step. 5. The flexible connection substrate connected to the liquid crystal panel substrate, or the protrusion formed on the surface of the electrode terminal of the driving TAB is the flexible connection substrate or the driving TA.
An electrode projection forming method, which is formed simultaneously with the cutting during the step of cutting B into a single piece.