JP4374642B2 - Film with conductive thin film and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates generally to finely separated linear conductive thin film / substrate systems. The range of the thickness of the conductive thin film and the thickness of the substrate varies, but the present invention is not particularly limited by the thickness.
[0002]
[Prior art]
In recent years, conductive thin film materials have been widely used throughout the industry. In particular, the transparent conductive thin film material is used as an electrode for driving a matrix of a liquid crystal display or the like, and the demand is rapidly increasing. A cross section of a general liquid crystal display is shown in FIG. Usually, a transparent conductive thin film (hereinafter referred to as “conductive film” unless otherwise specified) 20 is formed on one side of each of two glass plates 21 sandwiching a liquid crystal 22 when used in a liquid crystal display. . Recently, a plastic plate (film) may be used instead of a glass plate to reduce the weight and flexibility of the display itself. Also in this case, the conductive film is formed on one side of each of the two plastic plates (films).
[0003]
However, when used as an electrode for driving a matrix of a display, an initially isotropic conductive film is electrically etched by very troublesome pattern etching and the like, as shown in FIG. Are processed into a series of isolated strip-shaped elements, and each element is connected to a drive circuit.
The processed conductive film (attached glass plate) is shifted by 90 degrees from each other as shown in FIG. When a voltage is applied to an arbitrary display matrix element (i, j), the voltage is applied to the i-th strip element on one side and the j-th element on the other side.
[0004]
In other words, since the conductive film is usually formed uniformly and electrically isotropically, when it is used as an electrode of a display, processing steps such as lithography and pattern etching for subdividing in one direction are required.
In fact, this process involves many processes such as masking and exposure to photo-curing resin for pattern formation before pattern etching, and each process requires high accuracy, and is often a problem in the manufacturing process. It has become.
[0005]
[Problems to be solved by the invention]
The present invention has been made paying attention to the above-mentioned problems, and the problem is that the conductive thin film can be connected to the adjacent wiring by a simple method without complicated processes such as lithography and etching. It is an object to provide a film with a conductive thin film having electrical insulation. According to the present invention, for example, a process for manufacturing a liquid crystal display is greatly simplified, and a significant reduction in manufacturing cost can be expected.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the means provided by the present invention is as follows. First, in claim 1, a plurality of linear conductors formed on one side or both sides of a film-like insulating substrate and separated from each other by cracks. It is a film with a conductive thin film characterized by comprising a conductive thin film wiring and cracks in the conductive thin film being closed with a non-conductor .
[0007]
Moreover, in Claim 2, it is a film with an electroconductive thin film of Claim 1 whose fracture strain of the said film-like insulating base material is larger than the fracture strain of the said electroconductive thin film.
[0008]
According to a third aspect of the present invention, a conductive thin film is formed on one or both surfaces of a film-like insulating base material having a breaking strain larger than that of the conductive thin film, and the material is pulled in one direction. A large number of cracks perpendicular to the tensile direction are generated, and a plurality of linear conductive thin film wirings separated from each other are formed, and the pulling of the material is stopped at least within the time when the conductive thin film causes buckling failure. A method for producing a film with a conductive thin film characterized by maintaining unidirectional conductivity even after unloading .
[0009]
4. The film with a conductive thin film according to claim 3 , wherein the pulling of the material is performed at least until the base material undergoes plastic deformation, and the unidirectional conductivity is maintained even after unloading. It is a manufacturing method .
[0012]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, first, when the fracture strain of the base material is larger than that of the thin film in the material of the two-layer structure generally consisting of the thin film / base material, the crack generated in the thin film when the thin film / base material system is pulled in one direction Is described.
[0013]
FIGS. 1A and 1B are explanatory views when a thin film / base material is pulled in one direction. FIG. 1A shows a case where the tensile force is less than the critical strain of the thin film 1, and FIG. is there. The thin film 1 extends to the same extent as the thin film 1 and the substrate 2 up to the critical strain, but when the strain reaches the critical value of the thin film 1, only the thin film 1 has a crack perpendicular to the pulling direction. When the film is further pulled, if the adhesion between the thin film / substrate remains, the thin film 1 is pulled through the shear stress at the interface, and further cracks 3 are generated almost evenly on the thin film surface. It will be in the state where the shape elements were lined up continuously.
[0014]
Next, the case of a conductive thin film / film (substrate) insulating base material will be described. In general, the tensile critical strain of a conductive thin film is smaller than that of a film (substrate) -like insulating base material, so that the conductive thin film is cracked by pulling in one direction as described above. It becomes a row of strip-shaped elements elongated in the direction. At this time, the resistance in the long side direction of the strip (perpendicular to the pulling direction) remains almost the same as before the film breaks, but each strip element is electrically insulated by cracks, so at first, etc. A conductive thin film having conductivity in a lateral direction has a large resistance value in the short side direction (tensile direction). Therefore, the row of strip-shaped elements elongated in one direction becomes a wiring of a large number of linear conductive thin films.
Thereby, the film (substrate) with a conductive thin film on which the conductive film is formed acts as a film (substrate) with a unidirectional transparent conductive thin film including a plurality of conductive thin film wirings processed into strip-shaped elements. It becomes an electrode that can drive a liquid crystal display or the like as it is.
[0015]
【Example】
Next, examples of a film (plate) with a unidirectional transparent conductive thin film and a manufacturing method thereof according to the present invention will be described in more detail with reference to the drawings.
[0016]
<Example 1>
As a specific material, a PET film having a thickness of 100 μm was formed on a film (plate) -like insulating base material, an ITO thin film was formed as a conductive thin film, and the entire surface was uniformly formed on one side of the base material using a winding film forming apparatus. A sample was used as a sample. The thickness of the ITO thin film was 150 nm. Loresta AP (Mitsubishi Yuka) was used to measure the surface electrical resistance of the ITO film. As a result of measuring the surface electrical resistance of the film-formed sample, a value of 300Ω / □, which is almost constant in the in-plane direction of the film, was obtained.
[0017]
Next, this sample was set in a unidirectional tensile tester and pulled until a crack was generated in the ITO thin film (about 2.2%). The crack which arose in the ITO thin film at this time is shown in FIG. It can be seen that the thin film has elongated strips arranged in one direction due to the crack. Subsequently, the sample was removed from the testing machine and unloaded, and the surface electric resistance was measured by a normal method. For the measurement, a resistance value was measured with a four-terminal method using Loresta AP (Mitsubishi Yuka). The results are shown in FIG. The horizontal axis of the figure shows the angle deviation between the crack and the four-terminal probe. When the probe and the crack are parallel, the deviation is 0 degrees. The vertical axis represents the logarithmic value of the measured resistance value normalized by the resistance value at 0 degree with no cracks sandwiched. The initial resistance value in the crack direction is not much different from the initial resistance value, but when the angle is slightly deviated from the initial resistance value, an abrupt increase in resistance is shown, indicating that it has extremely sharp unidirectional conductivity characteristics. However, in order to have such a sharp unidirectional conductive characteristic, attention must be paid to the final tensile rate of the material. In other words, in the case of the ITO / PET system used in this example, cracks occur in ITO at about 1.0%, but if this is removed from the tester at this tensile rate and unloaded, cracks occur due to the elasticity of the PET film. Is closed again, the conductivity is restored, and the unidirectional conductivity is almost lost. That is, it is important to pull until the base material undergoes plastic deformation by pulling more than the yield strain of the base material so that the crack does not close after unloading. Since the yield strain of the PET film used in this example was about 2.0%, as described above, the sample pulled to about 2.2% continued to maintain sharp unidirectional conductivity characteristics after unloading. .
[0018]
Alternatively, if the substrate is not pulled until the substrate yields for other reasons, after the film (plate) material with the transparent conductive thin film is pulled to the desired value, the non-conductive coating is newly applied on the thin film in the pulled state. It is effective that the crack is closed with a nonconductor. In addition, although the residual strain is large, even if it is used as a display electrode in a state where the material is pulled, the crack is opened, so that the unidirectional conductivity characteristic is maintained.
[0019]
By the way, as described above, the thin film breaks first with many crack-like breaks perpendicular to the tensile direction. If the pulling is continued, many fractures parallel to the pulling direction occur. FIG. 4 shows the state in which these destructions occur.
When the thin film and the substrate are compressed by the Poisson effect in the direction perpendicular to the tensile direction, the Poisson's ratio differs between the thin film and the substrate (usually (Boisson ratio of the substrate)> (Boisson ratio of the thin film). )), And is referred to as buckling failure in this specification.
[0020]
If the material is pulled until this failure occurs, the high conductivity properties in the direction of the crack 4 are lost, so it is important that the final tensile rate remains before the pack ring failure 5 occurs. Incidentally, even in the case of the material of this example, the initial buckling fracture was seen from around 5%, and when it was in such a high tensile state, the surface resistance value in the crack direction was increased.
[0021]
It should be noted that the present invention is also effective for materials other than those used in the present embodiment when the fracture strain of the substrate is larger than that of the thin film. Moreover, it is also possible to form a conductive thin film on both surfaces of a base material and generate cracks for use.
[0022]
<Example 2>
Next, a liquid crystal display was produced using the unidirectional conductive film produced in Example 1. FIGS. 5A and 5B are conceptual diagrams showing the display in a plane. FIG. 5A is an overall plan conceptual diagram, and FIG. 5B is a partially enlarged plan conceptual diagram. The portions other than the unidirectional conductive film according to the present invention have the same structure as the conventional liquid crystal display shown in FIGS. 6 and 7, and the production method is the same.
[0023]
First, two unidirectional conductive films obtained in Example 1 were prepared for an upper electrode and a lower electrode. Thereafter, an upper electrode 8 for driving and a lower electrode 7 were provided. The electrodes 7 and 8 were provided by vapor-depositing a metal material on a film and patterning, etching, or the like using a normal photolithography technique. At this time, each electrode was created so that the electrodes were electrically insulated by one or more cracks (for upper electrode) 10 and (for lower electrode) 9. Next, these films are pasted on the two glass plates (no electrical conductivity) constituting the liquid crystal panel, and the two glass plates are placed on the upper electrode, and each is rotated 90 degrees and pasted. It was. At this time, the intersecting portion of the strip-shaped thin film wirings connected to the upper and lower electrodes becomes the display matrix element 6. In addition, when the glass is pasted, an alignment film is formed and aligned in advance on the side corresponding to the inner side between the two glasses in the same manner as a method for producing a normal liquid crystal panel. Next, liquid crystal sealing or the like was performed to obtain a liquid crystal panel. This was connected to an experimental simple matrix drive circuit (64 pixels * 64 pixels, 36 dpi) to perform display display. As a result, good matrix driving was observed with high accuracy as a liquid crystal display, and the usefulness of the present invention was confirmed.
[0024]
【The invention's effect】
According to the present invention, a film (plate) with a conductive thin film having isotropic conductivity at first is electrically isolated in one direction by simply pulling in one direction without using a complicated process such as etching. It is possible to produce a film (plate) with a unidirectional (transparent) conductive thin film by processing it into a row of elongated strip-like elements.
Thereby, for example, the process for manufacturing a liquid crystal display is greatly simplified, and a significant reduction in manufacturing cost can be expected.
[Brief description of the drawings]
BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is an explanatory view of a thin film crack caused by unidirectional pulling of a thin film / base material, (a) is an explanatory view when the tensile force is equal to or lower than the critical strain of the thin film, and (b) is a tensile strain that is critical strain. Explanatory drawing in the above case.
FIG. 2 is a plan view showing a pattern of cracks generated in the thin film after the ITO thin film / PET film sample was pulled about 2.2%.
FIG. 3 is a characteristic diagram showing in-plane anisotropy of surface electrical resistance after pulling 2.2% of an ITO / PET sample.
FIG. 4 is a plan view showing a pattern of buckling breakage occurring in an ITO thin film.
FIG. 5 is a conceptual diagram showing an example of matrix driving of a liquid crystal display using a film with a unidirectional transparent conductive thin film.
FIG. 6 is an explanatory view showing the concept of a general liquid crystal display in section.
7A and 7B are explanatory diagrams showing a general liquid crystal display electrode and its matrix driving, in which FIG. 7A is an explanatory diagram showing the mutual relationship between the transparent conductive thin film, the substrate, and the liquid crystal, and FIG. Explanatory drawing showing a relationship.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Thin film 2 ... Base material 3 ... Crack 4 ... Crack 5 ... Buckling destruction 6 ... Display matrix element 7 ... Lower electrode for drive 8 ... Upper part for drive Electrode 9 ... Lower electrode crack 10 ... Upper electrode crack 20 ... Transparent conductive thin film 21 ... Glass plate (plastic film plate)
22 ... Liquid crystal

Claims (4)

It is formed on one or both sides of a film-like insulating base material, and it has a large number of linear conductive thin-film wirings separated from each other by cracks. A film with a conductive thin film characterized by comprising: The film with a conductive thin film according to claim 1, wherein a fracture strain of the film-like insulating substrate is larger than a fracture strain of the conductive thin film. A conductive thin film is formed on one or both sides of a film-like insulating base material whose fracture strain is larger than that of the conductive thin film, and the material is pulled in one direction, and a crack perpendicular to the tensile direction is formed. A large number of wires are formed , which are separated from each other to form a plurality of linear conductive thin-film wirings. The pulling of the material is stopped at least within the time when the conductive thin-film breaks down. The manufacturing method of the film with an electroconductive thin film characterized by maintaining property . The method for producing a film with a conductive thin film according to claim 3 , wherein the pulling of the material is performed at least until the base material undergoes plastic deformation, and the unidirectional conductivity is maintained even after unloading.

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