Capacitive touch screen and method of making same

• US 8,354,143 B2
• Filed: 05/25/2006
• Issued: 01/15/2013
• Est. Priority Date: 05/26/2005
• Status: Active Grant

• Current Assignee: TPK Touch Solutions (Xiamen) Inc. (TPK Holding Co., Ltd.)
• Original Assignee: TPK Touch Solutions (Xiamen) Inc. (TPK Holding Co., Ltd.)
• Inventors: Halsey, Eugene L. IV, Cherif, Mondher
• Primary Examiner(s): Meeks, Timothy
• Assistant Examiner(s): TADAYYON ESLAMI, TABASSOM
• Application Number:
  US11/440,855
• Publication Number:
  US 20060266640A1
• Time in Patent Office: 2,427 Days
• Field of Search: 204/192.29, 204/129.25, 427/58, 427/372.2, 427/487, 427/98.3, 427/404, 427/419.2, 427/419.3, 427/419.4
• US Class Current: 427/372.2
• CPC Class Codes: G06F 3/0445 using two or more layers of sensing electrodes, e.g. using two layers of electrodes separated by a dielectric layer

Abstract

A capacitive touch screen and method of manufacturing such a touch screen includes providing a substrate and coating a surface of the substrate with a transparent conductive coating. An uncured conductive electrode material, such as an uncured silver epoxy material or an uncured silver or equivalent conducting metallic paste material, is disposed at least over a portion of the transparent conductive coating to establish a precursor of at least one metallic electrode at the substrate surface. A precursor of a protective hardcoat is established at least over the transparent conductive coating and/or the metallic electrode. Such precursor/undercured/uncured layers are then cured via a single common curing/firing process, which may heat the substrate and coatings to an elevated temperature, such as at about 500 degrees Celsius or above.

Claims

1. A method of manufacturing a touch screen, said method comprising:

providing a substrate;

coating by sputtering in a sputter chamber an unheated surface of said substrate with an uncured conductive coating, said uncured conductive coating comprising an indium/tin/suboxide thin film coating;

disposing at said unheated substrate surface an uncured conductive paste material at least over a portion of said uncured conductive coating to establish a precursor of at least one conductive electrode at said substrate surface;

disposing at said unheated substrate surface an uncured hardcoat material over at least one of said uncured conductive coating and said uncured conductive paste material to establish a precursor of a protective hardcoat at least over at least one of said uncured conductive coating and said uncured conductive paste material;

commonly heat curing said uncured hardcoat material, said uncured conductive coating and said uncured conductive paste material via a common thermal curing and firing process in a nitrogen rich atmosphere;

wherein said indium/tin/suboxide thin film coating is transformed during said common thermal curing and firing process to a cured indium tin oxide transparent conductive coating suitable for use for a touch screen, and wherein said cured indium tin oxide transparent conductive coating has a sheet resistance of less than about 8000 ohms per square;

wherein said uncured conductive paste material is transformed during said common thermal curing and firing process to at least one cured conductive electrode suitable for use for a touch screen; and

wherein said uncured hardcoat material is transformed during said common thermal curing and firing process to a cured protective hardcoat suitable for use for a touch screen.

2. The method of claim 1, wherein curing said uncured hardcoat material, said uncured conductive coating and said uncured conductive paste material via a common curing and firing process comprises curing by heating said substrate, said uncured hardcoat material, said uncured conductive coating and said uncured conductive paste material to an elevated temperature via a common curing and firing process.

3. The method of claim 2, wherein said elevated temperature is at least about 500 degrees Celsius.

4. The method of claim 1, wherein coating a surface of said substrate with an uncured conductive coating comprises depositing said uncured transparent conductive coating onto a substrate having a temperature of less than about 100 degrees Celsius.

5. The method of claim 1, wherein coating a surface of said substrate with an uncured conductive coating comprises coating a first surface of said substrate with an uncured conducive coating, said method including coating a second surface of said substrate with a second transparent conductive coating, said second surface being opposite said first surface.

6. The method of claim 5 including establishing a conductive coating at a perimeter region of said second surface transparent conductive coating.

7. The method of claim 1, wherein an oxygen content of indium tin is between about thirty percent and about fifty-five percent.

8. The method of claim 1, wherein said uncured conductive coating comprising an indium/tin/suboxide thin film coating has a transmissivity of light incident thereon of less than about forty-five percent.

9. The method of claim 1, wherein said cured indium tin oxide transparent conductive coating has a sheet resistance of at least about 400 ohms per square and wherein said touch screen comprises a capacitive touch screen.

10. A method of manufacturing a touch screen, said method comprising:

providing a substrate;

sputter coating an unheated surface of said substrate with an uncured conductive coating comprising an indium/tin/suboxide thin film coating;

wherein said sputter coating comprises sputter coating an unheated surface of said substrate with an uncured conductive coating via sputter coating in a sputter chamber;

disposing at said unheated substrate surface an uncured conductive paste material at least over a portion of said uncured conductive coating to establish a precursor of at least one conductive electrode at said substrate surface, wherein said uncured conductive paste material comprises an uncured silver epoxy material;

disposing at said unheated substrate surface an uncured hardcoat material over at least one of said uncured conductive coating and said uncured conductive paste material to establish a precursor of a protective hardcoat at least over at least one of said uncured transparent conductive coating and said uncured conductive paste material;

commonly heat curing said uncured hardcoat material, said uncured conductive coating and said uncured conductive paste material via a common thermal curing and firing process in a nitrogen rich atmosphere;

wherein said indium/tin/suboxide thin film coating is transformed during said common thermal curing and firing process to a cured indium tin oxide transparent conductive coating suitable for use for a touch screen, and wherein said cured indium tin oxide transparent conductive coating has a sheet resistance of less than about 8000 ohms per square;

wherein said uncured conductive paste material is transformed during said common thermal curing and firing process to at least one cured conductive electrode suitable for use for a touch screen; and

wherein said uncured hardcoat material is transformed during said common thermal curing and firing process to a cured protective hardcoat suitable for use for a touch screen.

11. The method of claim 10, wherein curing said hardcoat material, said uncured conductive coating and said uncured conductive paste material via a common curing and firing process comprises curing by heating said substrate, said uncured hardcoat, said uncured conductive coating and said uncured conductive paste material to an elevated temperature via a common curing and firing process, wherein said elevated temperature is at least about 500 degrees Celsius.

12. The method of claim 10, wherein sputter coating an unheated surface of said substrate with an uncured conductive coating comprises depositing said uncured conductive coating onto a substrate having a temperature of less than about 100 degrees Celsius.

13. The method of claim 10, wherein sputter coating a surface of said substrate with an uncured conductive coating comprises sputter coating a first surface of said substrate with an uncured conductive coating, said method including coating a second surface of said substrate with a second surface transparent conductive coating, said second surface being opposite said first surface.

14. The method of claim 13 including establishing a conductive coating at a perimeter region of said second surface transparent conductive coating.

15. The method of claim 10, wherein an oxygen content of indium tin is between about thirty percent and about fifty-five percent.

16. The method of claim 10, wherein said uncured conductive coating comprising an indium/tin/suboxide thin film coating has a transmissivity of light incident thereon of less than about forty-five percent.

17. A method of manufacturing a touch screen, said method comprising:

providing a substrate;

coating an unheated first surface of said substrate with a first uncured conductive coating, said first uncured conductive coating comprising an indium/tin/suboxide thin film coating;

wherein coating an unheated first surface of said substrate comprises coating an unheated first surface of said substrate with a first uncured conductive coating via sputter coating in sputter chamber;

disposing at said unheated substrate surface an uncured conductive material at least over a portion of said uncured conductive coating to establish a precursor of at least one electrode at said first surface of said substrate;

disposing at said unheated substrate surface an uncured hardcoat material over at least one of said first uncured conductive coating and said uncured conductive material to establish a precursor of protective hardcoat at least over at least one of said uncured conductive coating and said uncured conductive material;

coating a second surface of said substrate with a second uncured conductive coating;

commonly heat curing said uncured hardcoat material, said first uncured transparent conductive coating and said uncured conductive material via a common thermal curing and firing process in a nitrogen rich atmosphere;

wherein said indium/tin/suboxide thin film coating is transformed during said common thermal curing and firing process to a cured indium tin oxide transparent conductive coating suitable for use for a touch screen, and wherein said cured indium tin oxide transparent conductive coating has sheet resistance of at least about 400 ohms per square and less than about 8000 ohms per square;

wherein said uncured conductive material is transformed during said common thermal curing and firing process to at least one cured electrode suitable for use for a touch screen; and

wherein said uncured hardcoat material is transformed during said common thermal curing and firing process to a cured protective hardcoat suitable for use for a touch screen.

18. The method of claim 17, wherein curing said uncured hardcoat material, said first uncured conductive coating and said uncured conductive material via a common curing and firing process comprises curing by heating said substrate, said uncured hardcoat material, said first uncured conductive coating and said uncured conductive material to an elevated temperature via a common curing and firing process.

19. The method of claim 17, wherein coating a first surface of said substrate with a first uncured conductive coating comprises depositing said first uncured conductive coating onto a substrate having a temperature of less than about 100 degrees Celsius.

20. The method of claim 17, wherein an oxygen content of indium tin is between about thirty percent and about fifty-five percent.

21. The method of claim 17, wherein said uncured conductive coating comprising an indium/tin/suboxide thin film coating has transmissivity of light incident thereon of less than about forty-five percent.

22. A method of manufacturing a touch screen, said method comprising:

providing a substrate;

coating by sputtering in a sputter chamber an unheated surface of said substrate with an uncured conductive coating, said uncured conductive coating comprising an indium/tin/suboxide thin film coating;

disposing at said unheated substrate surface an uncured conductive paste material at least over a portion of said uncured conductive coating to establish a precursor of at least one conductive electrode at said substrate surface;

commonly heat curing said uncured conductive coating and said uncured conductive paste material via a common thermal curing and firing process;

wherein, said indium/tin/suboxide thin film coating is transformed during said common thermal curing and firing process to a cured indium tin oxide transparent conductive coating suitable for use for a capacitive touch screen, and wherein said cured indium tin oxide transparent conductive coating has a sheet resistance of at least about 400 ohms per square and less than about 8000 ohms per square; and

wherein said uncured conductive paste material is transformed during said common thermal curing and firing process to at least one cured conductive electrode suitable for use for a capacitive touch screen.

23. The method of claim 22, wherein curing said uncured conductive coating and said uncured conductive paste material via a common curing and firing process comprises curing by heating said substrate, said uncured conductive coating and said uncured conductive paste material to an elevated temperature via a common curing and firing process.

24. The method of claim 22, wherein coating an unheated surface of said substrate with an uncured conductive coating comprises depositing said uncured transparent conductive coating onto a substrate having a temperature of less than about 100 degrees Celsius.

25. The method of claim 22, further comprising:

disposing at said unheated substrate surface an uncured hardcoat material over at least one of said uncured conductive coating and said uncured conductive paste material to establish a precursor of a protective hardcoat at least over at least one of said uncured conductive coating and said uncured conductive paste material; and

heat curing said uncured hardcoat material to transform said uncured hardcoat material to a cured protective hardcoat suitable for use for a capacitive touch screen.