Method for making touch panel

• US 8,585,855 B2
• Filed: 09/29/2008
• Issued: 11/19/2013
• Est. Priority Date: 12/21/2007
• Status: Active Grant

• Current Assignee: Hon Hai Precision Industry Co., Ltd., Tsinghua University
• Original Assignee: Hon Hai Precision Industry Co., Ltd., Tsinghua University
• Inventors: Jiang, Kai-Li, Liu, Liang, Fan, Shou-Shan
• Primary Examiner(s): Lee, Katarzyna Wyrozebski
• Assistant Examiner(s): Patel, Vishal I
• Application Number:
  US12/286,175
• Publication Number:
  US 20090159188A1
• Time in Patent Office: 1,877 Days
• Field of Search: 156/281, 156/247
• US Class Current: 156/281
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact

Abstract

A method for making a touch panel includes the steps of: (a) providing a flexible substrate; (b) applying at least one carbon nanotube layer on the flexible substrate; (c) heat-pressing the carbon nanotube layer on the flexible substrate; (d) locating two electrodes on opposite ends of the flexible substrate; (e) placing an insulative layer on edges of a first surface of the flexible substrate, the first surface having the carbon nanotube layer formed thereon; and (f) securing the first electrode plate to a second electrode plate, with the insulative layer located between the first electrode plate and the second electrode plate, and wherein the carbon nanotube layer of the first electrode plate is adjacent to a carbon nanotube layer of the second electrode plate.

Claims

1. A method for making a touch panel, the method comprising the steps of:

(a) providing a flexible substrate having a first surface;

(a1) drawing at least two carbon nanotube films directly from a super-aligned carbon nanotube array;

(b) applying a transparent carbon nanotube layer on the first surface of the flexible substrate, wherein the transparent carbon nanotube layer is formed by stacking the at least two carbon nanotube films, each of the at least two carbon nanotube films comprises a plurality of carbon nanotubes aligned substantially along a same direction and parallel to the first surface of the flexible substrate, the at least two carbon nanotube films are directly stacked with each other, and an angle is formed between the aligned directions of the carbon nanotubes in adjacent carbon nanotube films;

(c) heat-pressing the transparent carbon nanotube layer on the flexible substrate;

(d) locating two electrodes on opposite ends of the flexible substrate;

(e) placing an insulative layer on edges of the first surface of the flexible substrate, the first surface having the transparent carbon nanotube layer formed thereon to form a first electrode plate;

(h) repeating steps (a) to (e) to obtain a second electrode plate; and

(f) securing the first electrode plate to the second electrode plate, with the insulative layer located between the first electrode plate and the second electrode plate, and wherein the transparent carbon nanotube layer of the first electrode plate is adjacent to the transparent carbon nanotube layer of the second electrode plate.

2. The method as claimed in claim 1, wherein each of the at least two carbon nanotube films is fabricated by the steps of:

(g1) providing an array of carbon nanotubes; and

(g2) pulling out each of the at least two carbon nanotube films from the array of carbon nanotubes by using a tool.

3. The method as claimed in claim 1, wherein before step (b), a step of cleaning the flexible substrate and coating the flexible substrate with a low melting material is executed.

4. The method as claimed in claim 3, wherein an organic solvent is used to clean the flexible substrate, and the organic solvent comprises ethanol, acetone or a combination thereof.

5. The method as claimed in claim 3, wherein the low melting material is coated on the flexible substrate by sputtering or spraying, and the melting point of the low melting material is lower than that of the flexible substrate and the carbon nanotube layers.

6. The method as claimed in claim 1, wherein (b) comprises the steps of:

(b1) laying the at least two carbon nanotube films on a surface of a supporter;

(b2) removing the supporter to form a free-standing carbon nanotube film structure; and

(b3) placing the carbon nanotube film structure on the first surface of the flexible substrate, so as to form the carbon nanotube layer.

7. The method as claimed in claim 6, wherein in step (b), a step of using an organic solvent to treat the at least two carbon nanotube films, the carbon nanotube film structure, or the carbon nanotube layer is executed.

8. The method as claimed in claim 1, wherein the angle is in a range from above 0°

to less than or equal to 90°

.

9. The method as claimed in claim 1, wherein the step (c) comprises the substeps of:

(c1) locating the flexible substrate with the carbon nanotube layer formed thereon in a hot-pressed device;

(c2) heating a pressing device of the hot-pressed device; and

(c3) squeezing the flexible substrate by the pressing device.

10. The method as claimed in claim 9, wherein the hot-pressed device comprises two rollers.

11. The method as claimed in claim 1, wherein step (d) further comprises the substeps of:

(d1) applying a conductive silver paste on the flexible substrate by means of screen printing or spraying; and

(d2) baking the flexible substrate in an oven for 10-60 minutes at a temperature in an approximate range from 100°

C. to 120°

C. to solidify the conductive silver paste.

12. The method as claimed in claim 1, wherein step (e) is executed by applying a layer of insulative adherent agent.

13. The method as claimed in claim 1, further comprising the steps of applying a slurry layer comprising a plurality of dot spacers on one of the first or the second electrode plates;

and drying the slurry layer.

14. The method as claimed in claim 1, further comprising adhering a transparent protective layer on a first surface of the touch panel by an adhesive, and the adhesive is a silver-based slurry.

15. The method as claimed in claim 14, wherein a material of the transparent protective layer is selected from the group consisting of silicon nitride, silicon dioxide, benzocyclobutenes, polyester film, and polyethylene terephthalate.

16. The method as claimed in claim 14, further comprising placing a shielding layer on a second surface of the touch panel, and a material of the shielding layer is at least one carbon nanotube film, and the at least one carbon nanotube film comprises a plurality of carbon nanotubes arranged along a same direction.

17. The method as claimed in claim 16, wherein the shielding layer is adhered to the second surface of the touch panel by an adhesive, and the adhesive is a silver-based slurry.

18. A method for making a touch panel, the method comprising the steps of:

(a) providing a flexible substrate having a first surface;

(b) stacking at least two carbon nanotube films directly on the first surface of the flexible substrate to form a transparent carbon nanotube layer, wherein each of the at least two carbon nanotube films comprises a plurality of carbon nanotubes aligned along a same direction and joined end to end by van der Waals force and parallel to the first surface of the flexible substrate, and the at least two carbon nanotube films are directly in contact with each other, wherein each of the at least two carbon nanotube films are obtained by the steps of;

providing a substantially flat and smooth substrate;

forming a catalyst layer on the substrate;

annealing the substrate with the catalyst layer in air at a temperature in the approximate range from 700°

C. to 900°

C. for about 30 to 90 minutes;

heating the substrate with the catalyst layer to a temperature in the approximate range from 500°

C. to 740°

C. in a furnace with a protective gas therein;

supplying a carbon source gas to the furnace for about 5 minutes to 30 minutes and growing a super-aligned array of carbon nanotubes on the substrate;

selecting one or more carbon nanotubes having a predetermined width from the array of carbon nanotubes;

pulling the carbon nanotubes directly from the array of carbon nanotube, to form carbon nanotube segments at an uniform speed to achieve the carbon nanotube film;

(c) heat-pressing the transparent carbon nanotube layer on the flexible substrate;

(d) locating two electrodes on opposite ends of the flexible substrate;

(e) placing an insulative layer on edges of the first surface of the flexible substrate, the first surface having the transparent carbon nanotube layer formed thereon to form a first electrode plate;

(h) repeating steps (a) to (e) to obtain a second electrode plate; and

(f) securing the first electrode plate to the second electrode plate, with the insulative layer located between the first electrode plate and the second electrode plate, and wherein the transparent carbon nanotube layer of the first electrode plate is adjacent to the transparent carbon nanotube layer of the second electrode plate.

19. The method as claimed in claim 18, wherein each of the at least two carbon nanotube films have a width of approximately 10 centimeters.

20. A method for making a touch panel, the method comprising the steps of:

(a) providing a flexible substrate having a surface;

(b) applying a transparent carbon nanotube layer on the surface of the flexible substrate, wherein the transparent carbon nanotube layer is formed by stacking at least two carbon nanotube films, each of the at least two carbon nanotube films comprises a plurality of carbon nanotubes aligned substantially along a same direction and parallel to the surface of the flexible substrate, the at least two carbon nanotube films are directly stacked with each other, and an angle is formed between the aligned directions of the carbon nanotubes in adjacent carbon nanotube films, wherein each of the at least two carbon nanotube films has a width of approximately 10 centimeters;

(c) adhering the carbon nanotube layer adhering firmly on the substrate by dropping a volatilizable organic solvent onto the transparent carbon nanotube layer to soak the transparent carbon nanotube layer;

(d) heat-pressing the transparent carbon nanotube layer on the flexible substrate;

(e) locating two electrodes on opposite ends of the flexible substrate;

(f) placing an insulative layer on edges of the surface of the flexible substrate to form a first electrode plate on the surface;

(h) repeating steps (a) to (f) to obtain a second electrode plate; and

(i) securing the first electrode plate to the second electrode plate, with the insulative layer located between the first electrode plate and the second electrode plate, and wherein the transparent carbon nanotube layer of the first electrode plate is adjacent to the transparent carbon nanotube layer of the second electrode plate.