Method of patterning electrically-conductive film on a flexible substrate

A method of patterning a combined layer of an electrically-conductive film, such as indium-tin-oxide (ITO), that is disposed on a flexible substrate includes bending the combined layer about a radius of curvature. The combined layer is initially bent in a first direction so that the electrically-conducive film is distal to the radius of curvature, so as to form initial dielectric lines in the electrically-conductive film. The combined layer is then bent in another direction so that the electrically-conductive film is proximate to the radius of curvature to further enhance the dielectric performance of the initial dielectric lines. The dielectric lines electrically isolate a portion of the electrically-conductive film that is disposed therebetween, to form an electrically conductive electrode.

TECHNICAL FIELD

Generally, the present invention relates to methods of forming electrically-conductive electrodes. Particularly, the present invention relates to methods of forming electrically-conductive electrodes on flexible substrates. More particularly, the present invention relates to methods of forming patterned electrodes by controlling the cracking of a layer of electrically-conductive film, such as indium-tin-oxide (ITO), that is disposed on a flexible substrate.

BACKGROUND OF THE INVENTION

Flat panel devices, such as flat-panel displays, including LC (liquid crystal) and plasma displays, and photovoltaic devices, utilize transparent, conductive electrodes to control various operating functions of the flat panel device. During fabrication of the flat panel device, the transparent, conductive electrodes are typically formed of a thin film of transparent, electrically-conductive material, such as indium-tin-oxide (ITO), which is vacuum-deposited on a transparent rigid glass substrate. The ITO film is patterned into optically-transparent electrodes using conventional photolithographic techniques. Such photolithographic techniques, however, require precise and accurate bonding of the electrodes to the driving circuitry of the display, which can be costly. Recently, however, the flat-panel device industry has sought to replace the use of rigid glass substrates with flexible substrates, such as those formed from flexible plastics and polymers, while still retaining the use of ITO, or other electrically-conductive polymers, to form the transparent electrodes using advanced printing and photolithographic techniques.

In addition, while indium-tin-oxide (ITO) has the desired optical and electrical properties required for such flat panel devices, ITO is brittle and is easily cracked when a flexible substrate upon which the ITO film is carried is bent or flexed. As such, flat panel electronic devices utilizing ITO tend to be fragile and require careful handling, and in some instances, cracking of the ITO film may result in reduced production yields of such flat panel electronic devices. In contrast, electrically-conductive polymers, which are an alternative to ITO, have the advantage of being more flexible than ITO and are able to be used in manufacturing processes of electronic devices that utilize printing and photolithographic techniques. However, as compared to ITO, electrically-conductive polymers have a variety of drawbacks, including reduced electrical conductivity and reduced light transmission.

Therefore, there is a need for a low-cost method of patterning an electrically-conductive film, such as indium-tin-oxide (ITO), into conductive electrodes on a flexible substrate. In addition, there is a need for a method of patterning an electrically-conductive film, such as indium-tin-oxide (ITO), into conductive electrodes on a flexible substrate, which is compatible with continuous roll-to-roll manufacturing processes. Furthermore, there is a need for a method of patterning an electrically conductive film, such as indium-tin-oxide (ITO), into conductive electrodes that are precisely defined. In addition, there is a need for a method of patterning an electrically-conductive film, such as indium-tin-oxide (ITO), that is disposed on flexible substrates that is simple to execute and that eliminates the need for costly and environmentally-unfriendly materials and solvents.

SUMMARY OF THE INVENTION

In light of the foregoing, it is a first aspect of the present invention to provide a method of patterning a film comprising the steps of providing a flexible substrate having a electrically conductive film disposed thereon to form a combined layer; bending the combined layer about a radius of curvature to crack the electrically conductive film to form a plurality of dielectric lines in the electrically conductive film, such that each pair of consecutive dielectric lines defines and electrically isolates a conductive electrode therebetween.

It is another aspect of the present invention to provide a method of patterning a conductive film comprising, providing a flexible substrate having an electrically-conductive film disposed thereon to form a combined layer, bending the flexible substrate about a radius of curvature, moving the radius of curvature along the combined layer to form a plurality of dielectric crack lines in the conductive film, wherein each pair of the plurality of dielectric crack lines defines and electrically isolates a conductive section therebetween; inversely bending the flexible substrate about a radius of curvature, and moving the radius of curvature along the combined layer to form a plurality of dielectric crack lines in the conductive film, wherein each pair of the plurality of dielectric crack lines defines and electrically isolates a conductive section therebetween.

Another aspect of the present invention is to provide a method of patterning a conductive film comprising, providing a flexible substrate having an electrically-conductive film disposed thereon, and having an adhesive film disposed thereon, to form a combined layer, bending the flexible substrate about a radius of curvature, moving the radius of curvature along the combined layer to form a plurality of dielectric crack lines in the conductive film, wherein each pair of the plurality of dielectric crack lines defines and electrically isolates a conductive section therebetween, inversely bending the flexible substrate about a radius of curvature, moving the radius of curvature along the combined layer to form a plurality of dielectric crack lines in the conductive film, and detaching the adhesive film, wherein each pair of the plurality of dielectric crack lines defines and electrically isolates a conductive section therebetween.

An additional aspect of the present invention is to provide a method of patterning a conductive film comprising, providing a flexible substrate having an electrically-conductive film disposed thereon, so as to form a combined layer, providing first and second substantially parallel plates that are spaced apart by a gap, attaching a portion of the substrate to each first and second plate, such that the combined layer is bent across the gap with a radius of curvature, and sliding one of the first and second plates relative to the other, so as to bend the combined layer by the radius of curvature, so as to form a plurality of dielectric crack lines in the conductive film, whereby each pair of the plurality of dielectric crack lines defines and electrically isolates a conductive section therebetween, inversely attaching a portion of the substrate to each first and second plate, such that the combined layer is inversely bent across the gap with a radius of curvature, and sliding one of the first and second plates relative to the other, so as to inversely bend the combined layer by the radius of curvature, so as to form a plurality of dielectric crack lines in the conductive film, whereby each pair of the plurality of dielectric crack lines defines and electrically isolates a conductive section therebetween.

Still another aspect of the present invention is to provide a method of patterning a conductive film comprising, providing a flexible substrate having an electrically-conductive film disposed thereon, and having an adhesive film disposed thereon, to form a combined layer, providing first and second substantially parallel plates that are spaced apart by a gap, attaching a portion of the substrate to each first and second plate, such that the combined layer is bent across the gap with a radius of curvature, and sliding one of the first and second plates relative to the other, so as to bend the combined layer by the radius of curvature, so as to form a plurality of dielectric crack lines in the conductive film, whereby each pair of the plurality of dielectric crack lines defines and electrically isolates a conductive section therebetween, inversely attaching a portion of the substrate to each first and second plate, such that the combined layer is inversely bent across the gap with a radius of curvature, sliding one of the first and second plates relative to the other, so as to inversely bend the combined layer by the radius of curvature, and detaching the adhesive film, so as to form at plurality of dielectric crack lines in the conductive film, whereby each pair of the plurality of dielectric crack lines defines and electrically isolates a conductive section therebetween.

DETAILED DESCRIPTION OF THE INVENTION

A method of patterning an electrically-conductive film that is disposed on a flexible substrate to form electrically-conductive electrodes is provided by the present invention. In particular, a thin conductive film10, which may comprise indium-tin-oxide (ITO) or other suitable electrically conductive material, is applied upon a flexible substrate20to form a combined layer30, as shown inFIG. 1A. It should be appreciated that the conductive film10may be at least partially transparent to light. In addition, the flexible substrate20may comprise polyethylene terephthalate (PET), as well as any other suitably flexible material, such as plastic, or any other polymeric/elastomeric material for example. It should be appreciated that the flexible substrate may be at least partially transparent to light. The ITO film10may be applied or otherwise disposed on the flexible substrate20using any suitable process, such as sputtering or vacuum deposition for example. Once the ITO film10is disposed on the flexible substrate20, a stress force is applied to the combined layer30to crack the ITO film10into electrically isolated conductive sections. Specifically, the ability to crack the ITO film10is a result of its brittleness (i.e., inability to sustain a change in dimension without breaking) and the ability of the substrate20to be flexed.

In order to “crack” or fracture the electrically-conductive ITO film10in order to pattern it with non-conductive dielectric lines, stress is imparted to the ITO film10by either mechanical flexing/bending alone, or in combination with the application of thermal stress. Mechanical flexing is achieved by bending the combined layer30in a manner to be discussed, whereby the radius of curvature of the bend inversely controls the magnitude of the mechanical stress imparted to the substrate20and the ITO film10. That is, the smaller the radius of curvature used to form the bend, the greater the amount of mechanical stress that is applied to the substrate20and to the ITO film10. Alternatively, in the case of thermally heating the combined layer30, the substrate20and the conductive ITO film10have different coefficients of thermal expansion, such that changes in temperature produce a mechanical strain that is used to produce dielectric crack lines or dielectric lines in the conductive ITO film10.

Specifically, in one embodiment, the patterning process is carried out, such that after the conductive film10, such as ITO, is disposed on the flexible substrate20, mechanical stress is applied to the combined layer30by bending the substrate20to have a radius of curvature, designated as “R”, as shown inFIGS. 1B-C. The radius of curvature R may be created by outwardly bending (i.e., the ITO layer10is positioned on the outside, or positioned distal to the radius of curvature R) the combined layer30upon itself, as shown inFIG. 1B. Such outward bending can be achieved by outwardly bending the combined layer30around a substantially cylindrical section32, such as a rod, which forms the radius of curvature R. Thus, when the combined layer30is bent outwardly, the combined layer30extends around the radius of curvature R by a predetermined amount, such as about 180 degrees, as shown inFIG. 1B, to form a plurality of first or initial dielectric lines (dielectric crack lines)40, as shown inFIGS. 2A-B. It should be appreciated that the initial dielectric lines40are defined as regions in which gaps/voids or partial gaps in the conductive film10are formed, which act as a dielectric or electrical insulator. It should be appreciated that a pair of consecutive dielectric crack lines40formed in the ITO film10separate adjacent/neighboring conductive strips50, which form electrically conductive electrodes. As such, the dielectric lines40serve to electrically isolate adjacent conductive strips or electrodes50formed between a pair of consecutive dielectric lines40from other electrodes50.

In addition, to outwardly bending the combined layer30, the combined layer30may be inwardly (i.e. inversely) bent (i.e., the ITO layer10is positioned on the inside or positioned proximate to the radius of curvature R) around the radius of curvature R by a predetermined amount, such as about 180 degrees for example, as shown inFIG. 1C. Such inward bending of the combined layer30serves to improve or enhance the dielectric performance (i.e. dielectric strength) and the electrical isolation properties of the initial dielectric lines40by further cracking the initial dielectric lines40, so that improved or enhanced dielectric lines41are formed in the ITO film10, as shown inFIGS. 3A-B. That is, the stress imparted by bending the conductive ITO film10in two directions, outwardly and inwardly, forms a plurality of uniformly spaced, enhanced dielectric lines41in ITO film10, as shown inFIGS. 3A-B. The improved dielectric crack lines41are formed in the ITO film10as lines that extend in a direction that is substantially perpendicular to the direction in which the combined layer30is being bent with the radius R. That is, the dielectric lines40,41that are formed extend in the same direction as the axis from which the radius of curvature R extends. In one aspect, the dielectric lines40,41that are formed may extend in a direction so as to be substantially parallel to the axis from which the radius of curvature R extends. In addition, the spaced dielectric crack lines41define substantially uniform conductive strips or sections50therebetween in the ITO film10. It should be appreciated that the dielectric crack lines41space apart adjacent conductive sections50, and electrically isolate adjacent conductive strips or sections50from each other, allowing the conductive sections50to serve as electrically-conductive electrodes. It should also be appreciated that while all the first or initial dielectric crack lines40inFIGS. 2A-Bare shown as being formed into improved or enhanced dielectric crack lines41inFIGS. 3A-B, the process discussed herein may also be carried out so that none, or only a portion, of the initial dielectric crack lines40are formed into improved or enhanced dielectric crack lines41. It should also be appreciated in alternative embodiments, that the enhanced dielectric crack lines41may be formed in the ITO layer10by first inwardly bending the combined layer30, then outwardly bending the combined layer30.

Continuing with reference toFIGS. 1A-C, the stress imparted by the mechanical bending of the combined layer30, previously discussed, may be calculated in accordance with the following approach. It should be appreciated that the thickness of the conductive film or layer10is generally thinner than the thickness of the substrate20, and in some embodiments several orders of magnitude thinner. For example, the ITO layer or film10may have a thickness that is on the order of about 0.1 microns, while the thickness of the substrate20may be on the order of about 100-200 microns. As such, the thickness of the conductive film10is disregarded when calculating the stress applied to the combined layer30, as presented below. Specifically, with regard toFIG. 1B, in the case where the substrate20is formed of PET (polyethylene terephthalate) and is outwardly bent by 180 degrees around the curved section32having a radius of curvature “R,” the length of the inside surface of the substrate20that is adjacent to the radius of curvature R of the curved section32is equal to πR. The outside surface of the substrate20has a length that is longer than its inside surface, which allows the substrate20to accommodate the thickness, designated as “T1”, of the substrate film20. In addition, the length of the substrate20is equal to πT1, and the radius of curvature about which the substrate20is bent is increased to R+T1, making the total length of the film π(R+T1). As such, the stress can be expressed as the relative increase in length of the substrate20that is required to accommodate the bend and is defined by equation:

π⁡(R+T1)-π⁢⁢Rπ⁢⁢R,
which simplifies to T1/R. Thus, it is the ratio of the thickness of substrate20to the radius curvature R of the curved section32that is used to bend the combined layer30that defines the stress imparted to the combined layer30, which causes the first dielectric crack lines40to form in the conductive ITO film10. Then, the substrate20, which is formed of PET, is inwardly bent by about 180 degrees around the curved section32having a radius of curvature designated as “R”. Thus, the ratio of the thickness of substrate20to the radius of curvature R of the curved section32that is used to bend the combined layer30that defines the stress imparted to the combined layer30, causes the formation of enhanced dielectric crack lines41in the conductive ITO film10, as shown inFIGS. 3A-B, and thus results in the formation of enhanced cracked ITO electrodes.

In other words, as the flexible substrate20is outwardly bent around the radius of curvature R that is provided by the curved section32, as shown inFIG. 1B, the outside surface of the substrate20elongates, and/or the inside surface of the substrate20contracts, by an amount defined by the radius of curvature R and the thickness of the substrate T1, so as to accommodate the bend. The length of the outside surface of the substrate20exceeds the length of the inside surface of the substrate20about the bend by π times the thickness T1of the substrate20, as shown inFIG. 1B. As such, the relative amount of stress induced by the bend is equal to the ratio of the thickness T1of the substrate20relative to the radius of curvature R, such as that provided by the curved section32, that is being used to bend the combined layer30. For example, in the case where the substrate20comprises PET having a thickness T1of about 7 mils or about 0.17 mm, and is tightly bent around a curved section32having a radius of curvature R of 1 mm, the % change in the length of the substrate20will be approximately 17%, which is sufficient to produce first or initial dielectric lines40in the ITO film10, as shown inFIGS. 2A-B. Then, the flexible substrate20is inwardly bent around the radius of curvature R that is provided by the curved section32, as shown inFIG. 1C, the inside surface of the substrate20is squeezed, or otherwise compressed, which is sufficient to form the enhanced dielectric lines41in the ITO film10, as shown inFIGS. 3A-B. Therefore, because the enhanced dielectric crack lines41, which are formed by bending the combined layer30in two directions are wider than first dielectric lines40, which are formed by bending the combined layer30in one direction, the electrical isolation (i.e. resistance) between neighboring ITO electrodes50defined by the enhanced dielectric lines41is increased, thereby providing ITO electrodes50that have increased electrical isolation from one another.

First or initial dielectric crack lines40and enhanced dielectric crack lines41can be further enhanced or modified by applying an adhesive film or tape60to form a combined layer30′, as shown inFIG. 4. The adhesive tape60is applied onto the ITO film10with proper adhesion, whereby the adhesive tape60may comprise 3M Magic™ tape. Initially, in the same manner shown inFIG. 1B, the flexible substrate20is outwardly bent around the radius of curvature R that is provided by the curved section32, such that the outside surface of the substrate20is stretched, which is sufficient to produce first dielectric lines40in the ITO film10, as shown inFIGS. 2A-B. Next, the flexible substrate20is inwardly bent around the radius of curvature R that is provided by the curved section32in the same manner shown inFIG. 1C, so the inside surface of the substrate20is squeezed or otherwise compressed, which is sufficient to form enhanced dielectric lines41in the ITO film10, as shown inFIGS. 3A-B. Finally, the adhesive tape60is removed from ITO film10, whereupon any residual ITO flakes or particles that are generated from the formation of the dielectric lines40,41are removed, as the flakes are adhered to the adhesive tape60. Without their removal, such ITO flakes would otherwise traverse the dielectric lines40,41, decreasing the dielectric capability. Therefore, the dielectric crack lines41are further improved, because the electrical isolation along the direction, which is perpendicular to the direction of the conductive sections or electrodes50, is increased due to the removal of the ITO flakes.

In another embodiment, first or initial dielectric crack lines40and enhanced dielectric crack lines41can be further enhanced by the application of force to the combined layer30at high temperature, as the PET substrate20is easily stretched at temperatures above the glass transition temperature. Thus, the flexible PET substrate20can be uniformly stretched by applying forces in the direction, which is perpendicular to the dielectric crack lines40,41, while heating the combined layer30,30′ above the glass transition temperature. As such, the dielectric properties of the first dielectric crack lines40and enhanced dielectric crack lines41are improved by increasing their widths.

Thus, the first or initial dielectric crack lines40and the enhanced dielectric crack lines41formed in the conductive film10serve to disrupt or at least greatly reduce the electrical conductivity of the conductive film10. As such, the dielectric crack lines40form spaces or gaps in the conductive film10that serve as dielectric regions that electrically isolate conductive sections or strips50of conductive film10that are positioned between a pair of dielectric lines40,41. As such, the controlled cracking of the conductive ITO film10allows regular-spaced dielectric lines40,41to be formed that allow such a process to be used to form electrode patterns, such as a plurality of spaced electrodes50, in the conductive film10of a precise shape and dimension.

In order to form the first dielectric crack lines40and the enhanced dielectric crack lines41along a length of the conductive ITO film10of the combined layer30,30′ a rolling process is utilized, whereby the radius of curvature R is moved along the length of the combined layer30,30′, such that the length of the ITO film10is subjected to the mechanical bending forces previously discussed. This process may be performed by positioning the combined layer30between two thick, opposed, flat glass plates100and110that are spaced apart by a gap112of a predetermined distance, as shown inFIG. 5A. It should be appreciated that the plates100,110may be formed from any suitable material, such as aluminum, for example. In one aspect, the plates100and110may be separated by a rolling spacer114, such as a cylindrical rod or other rollable/moveable component, such as a roller, a ball bearing, or bead for example, to maintain the plates100,110in a substantially parallel arrangement, to define the radius of curvature R that is to be imparted to the combined layer30, and to facilitate the rolling/sliding movement of the plates100,110relative to each other.

Thus, as a first step of the rolling process, the combined layer30is positioned, such that one end of the ITO film10is attached to an inner surface120of the glass plate100, while the other end of the ITO film10is attached to an inner surface130of the other glass plate110, so the flexible substrate20is outwardly bent around the radius of curvature R, as shown inFIG. 5A. Next, the combined layer30is rolled between the two plates100,110, by moving the plates100,110in opposite directions, while the ITO film10and the substrate20are bent by an amount that is defined by the radius of curvature R that is determined by the size of the gap112. However, in other embodiments, the rolling process may be carried out, whereby one plate100,110is fixed in a stationary position, while the other plate100,110is permitted to move. As such, the plates100,110are maintained in their substantially parallel orientation during the rolling process. In one aspect, the flexible substrate20is bent by about 180 degrees around the radius of curvature R in this configuration. As such, first dielectric lines40form in the ITO film10along the bend or along the axis of curvature R in order to accommodate the stretch stress that is imparted by the radius of curvature R defined by the gap112.

In a next step in the rolling process, the flexible substrate20is inwardly bent around the radius of curvature R, as shown inFIG. 5B, whereby the combined layer30is positioned, such that one end of the flexible substrate20is attached to an inner surface120of the glass plate100, while the other end of the flexible substrate20is attached to an inner surface130of the other glass plate110. Once the combined layer30is attached to the plates100,110the plates100,110are moved in the manner discussed above with regard to the formation of the first dielectric lines40. As a result, enhanced dielectric crack lines41form in the ITO film10along the bend or along the axis of curvature R in order to accommodate the squeeze stress that is imparted by the radius of curvature R defined by the gap112. It should be appreciated that each step of outward bending and inward bending performed by the rolling process may be performed one or more times. In other embodiments, the steps of the rolling process may be performed individually or together in any desired sequence.

Thus, uniformly rolling a polyester PET substrate20that is coated with a thin film of indium-tin-oxide (ITO)10inwardly and outwardly, as discussed above, forms a pair of neighboring/consecutive first dielectric lines40that are separated by about 5-10 microns, which results in the formation of an electrode50therebetween having the same dimension. In addition, such rolling process forms a pair of neighboring/consecutive enhanced dielectric lines41that are separated by about 15-30 microns, which results in the formation of an electrode50therebetween having the same dimension. The cracks in the ITO film10form as lines that are perpendicular to the bend direction. It should also be appreciated that the width of the dielectric crack lines40,41themselves may have a width on the order of about 0.05 microns for example.

In another embodiment, first dielectric lines40and enhanced dielectric lines41may be further enhanced by applying an adhesive film60and positioning the combined layer30′ between two thick, opposed, flat glass plates100and110that are spaced apart by a gap112of a predetermined distance, utilizing the same rolling technique discussed above with regard toFIGS. 5A-B. Specifically, the adhesive film or tape60having a suitable adhesive, such as 3M Magic™ tape, is applied upon the ITO film10, as shown inFIG. 4, to form the combined layer30′. Then, the combined layer30′ is positioned, such that one end of the adhesive tape60is attached to an inner surface120of the glass plate100, while the other end of the adhesive tape60is attached to an inner surface130of the other glass plate110, so the flexible substrate20is outwardly bent around the radius of curvature R, in a similar manner to that shown in ofFIG. 5A. Next, the combined layer30′ is rolled between the two plates100,110, whereby the ITO film10and the substrate20are bent by an amount defined by the radius of curvature R that is determined by the size of the gap112. In one aspect, the flexible substrate20is bent by about 180 degrees in this configuration. As such, first dielectric crack lines40form in the ITO film10along the bend or along the axis of curvature R in order to accommodate the stretch stress that is imparted by the radius of curvature R defined by the gap112. Next, the flexible substrate20is inwardly bent around the radius of curvature R, as shown in the third part ofFIG. 3B, whereby the combined layer30is positioned, such that one end of the flexible substrate20is attached to an inner surface120of the glass plate100, while the other end of the flexible substrate20is attached to an inner surface130of the other glass plate110, in a similar manner to that shown inFIG. 5B. As such, enhanced dielectric crack lines41form in the ITO film10along the bend or along the axis of curvature R in order to accommodate the squeeze stress that is imparted by the radius of curvature R defined by the gap112. Next, the adhesive tape60is removed from the ITO film10, whereby the ITO flakes generated from the enhanced dielectric crack lines41are removed due to their adhesion to adhesive tape60. Therefore, the first dielectric crack lines40and the enhanced dielectric crack lines41are further improved because the electrical isolation along the direction, which is perpendicular to the direction of the conductive sections or strips50, are increased due to the removing of ITO flakes.

It should be appreciated that in other embodiments, Elmer's™ Glue, or any other suitable liquid adhesive, may also be used to remove the ITO flakes from the ITO film10. This is because the Elmer's™ Glue can be coated on the surface of the ITO film10in the liquid state, whereby the ITO flakes are surrounded by Elmer's™ Glue during this liquid-coating process. Then, after the Elmer's™ Glue has dried, the dried glue can be removed as a dried film, which entraps or contains the ITO flakes or particles. As such, the ITO layer20is coated with the Elmer's™ Glue after the squeeze (i.e. inward bending) step of the rolling process discussed above. It should be appreciated that the Elmer's™ Glue process may be used with or without the process of using the adhesive tape60.

Thus, in summary, one embodiment of the method contemplated by the present invention includes placing 3M Magic™ tape60upon the ITO layer10before rolling the combined layer30′→stretch rolling (outward bending) the combined layer30′→squeeze rolling (inward bending) the combined layer30′→ and removing the 3M Magic™ tape60from the combined layer30′. Another embodiment of the present invention includes stretch rolling (outward bending) the combined layer30→placing 3M Magic™ tape on the ITO layer10to form the combined layer30′→squeeze rolling (inward bending) the combined layer30′→removing the 3M Magic™ tape from the combined layer30′. Yet another embodiment of the present invention includes stretch rolling (outward bending) the combined layer30→squeeze rolling (inward bending) the combined layer30→placing the 3M Magic™ tape with the application of pressure or use Elmer's™ Glue on ITO layer10of the combined layer30→removing the 3M Magic™ tape or Elmer's™ Glue from the combined layer30; stretch rolling (outward bending) the combined layer30→squeeze rolling (inward bending) the combined layer without the use of adhesive tape60or glue.

As previously discussed, to achieve a further improvement in the dielectric performance of the dielectric crack lines40,41, the advantages of “3M Magic™ tape” and “Elmer's™ Glue” discussed herein may be combined, such that 3M Magic™ tape is placed on the ITO layer10before rolling of the combined layer30′→stretch rolling (outward bending) the combined layer30′→squeeze rolling (inward bending) the combined layer30′→removing the 3M Magic™ tape from the combined layer30′→coating the ITO film10with Elmer's™ Glue→blowing air from an air gun to dry the Elmer's™ Glue→removing the dried Elmer's™ Glue from the combined layer30. This process removes additional, fine ITO flakes remaining on the surface of the ITO layer10that have not been removed by the 3M Magic™ tape60.

Based on the foregoing, the advantages of the present invention are readily apparent. The main advantage of this invention is that a method of forming electrodes in a transparent, electrically conductive film, such as indium-tin-oxide (ITO) is carried out by the application of a bending force. Another advantage of the present invention is that a method of forming electrodes in a transparent, electrically conductive film, such as ITO, uses adhesive tape and/or glue to remove residual particles of the film that are generated as a bending force is applied thereto to form the electrodes to improve the electrical isolation of the electrodes.

Thus, it can be seen that the objects of the present invention have been satisfied by the structure and its method for use presented above. While in accordance with the Patent Statutes, only the best mode and preferred embodiment has been presented and described in detail, it is to be understood that the present invention is not limited thereto or thereby. Accordingly, for an appreciation of the true scope and breadth of the invention, reference should be made to the following claims.