Film coating method for improving resistance stability of flexible ITO (Indium Tin Oxide) film

Abstract

The invention provides a coating method for improving resistance stability of a flexible ITO (indium tin oxide) film, which belongs to the technical field of coating, and comprises the following steps: (1) loading a substrate film roll into a vacuum coating equipment chamber, and adjusting the vacuum degree in the vacuum coating equipment chamber; (2) unwinding a base material film roll, and adjusting the temperature in a cavity of vacuum coating equipment to heat and degas the film material; and (3) after degassing is completed, directly carrying out secondary winding to carry out ITO coating operation. According to the film coating method for improving the stability of the flexible ITO film resistor, the stability of the flexible ITO film resistor is guaranteed through pretreatment of the base material.

Description

Technical Field

[0001] The present invention relates to the field of coating technology, and particularly relates to a coating method for improving the resistance stability of a flexible ITO film. Background Art

[0002] A flexible transparent conductive film is a film made by coating a flexible substrate with materials such as metals or oxides through physical or chemical methods. Among them, the flexible ITO film is an indium tin oxide (ITO) film coated on a flexible substrate, which has the characteristics of transparent conductivity, and at the same time has high conductivity, high visible light transmittance, low resistivity, high mechanical hardness and good chemical stability. The flexible ITO film is the most commonly used thin film material for transparent electrodes of liquid crystal displays (LCDs), plasma displays (PDPs), electroluminescent displays (EL / OLEDs), touch panels (TouchPanels), solar cells and other electronic instruments.

[0003] Vacuum coating technology is a technology that deposits materials on the surface of a substrate to form a film through physical or chemical methods in a vacuum environment. This technology has the advantage of being able to operate under low-pressure conditions, avoiding the interference of impurities in the air on the coating process, thereby ensuring the purity and uniformity of the film layer. Vacuum coating technology has been applied to flexible ITO films. For example, the patent with the publication number CN103436844A and the name "A Coating Device and Method for Low-Temperature Deposition of Flexible Substrate ITO Films" discloses a device in which a substrate winding mechanism capable of forward and reverse rotation, an ion source, and an unbalanced intermediate-frequency magnetron sputtering mechanism are respectively arranged in a container body. The ion source is arranged outside the unwinding component of the substrate winding mechanism, and the unbalanced intermediate-frequency magnetron sputtering mechanism is arranged outside the main roller of the substrate winding mechanism; the outside of the container body is connected to a high-vacuum pumping mechanism, the input end of the substrate winding mechanism is connected to a workpiece conveying mechanism, and one end of the main roller of the substrate winding mechanism is connected to a heat exchange mechanism. The method is as follows: the workpiece conveying mechanism sends a sample; the high-vacuum pumping mechanism evacuates the container body; when the substrate winding mechanism conveys the flexible substrate, an unbalanced intermediate-frequency magnetron sputtering is used to deposit the flexible substrate ITO film at a low temperature. However, in the above scheme, if the substrate is a flexible substrate, such as a PET substrate, when there are impurity gases such as water vapor in the substrate, the release of the impurity gases during the coating process will contaminate the coating process and affect the resistance stability of the flexible ITO film. Summary of the Invention

[0004] In view of this, the present invention provides a coating method for improving the resistance stability of a flexible ITO film, and realizes the guarantee of the resistance stability of the flexible ITO film through the pretreatment of the substrate.

[0005] To achieve the above object, the present invention provides a coating method for improving the resistance stability of a flexible ITO film, including the following steps: (1) Load the substrate film roll into the chamber of the vacuum coating equipment and adjust the vacuum degree in the chamber of the vacuum coating equipment. (2) Unwind the substrate film roll and adjust the temperature in the chamber of the vacuum coating equipment to heat and degas the film material. (3) After degassing is completed, directly perform secondary winding for ITO coating operation.

[0006] Optionally, the adjusted vacuum degree in the chamber of the vacuum coating equipment is a pressure ≤ 5×10⁻ 5 mbar.

[0007] Optionally, the transmission tension for unwinding the substrate roll film is 30 - 100 N / m.

[0008] Optionally, the unwinding rate of the substrate roll film is 0.5 - 2 m / min.

[0009] Optionally, the heating and degassing is segmented heating. The temperature for the first-stage heating is 100 - 120 °C and the heating time is 5 - 10 min; the temperature for the second-stage heating is 130 - 150 °C and the heating time is 5 - 10 min.

[0010] Optionally, the subsequent ITO coating operation is to deposit the ITO layer by magnetron sputtering under the condition of maintaining a vacuum degree ≤ 5×10 -6 mbar, the sputtering power density is 3 - 5 W / cm², and the argon-oxygen flow ratio is controlled at 40:1 - 80:1.

[0011] Optionally, the thickness of the ITO layer is 80 - 200 nm. After deposition, plasma-assisted annealing is performed, the annealing temperature is 80 - 120 °C, and the time is 30 - 60 s.

[0012] Optionally, the substrate is polyimide or polyethylene terephthalate, and the thickness is 50 - 125 μm.

[0013] In order to achieve the above object, the present invention also provides a flexible ITO film prepared by a coating method for improving the resistance stability of the flexible ITO film.

[0014] The above technical solution of the present invention has at least the following beneficial effects: The technical solution provided by the present invention pre-treats the flexible substrate, that is, uses a vacuum coating equipment to remove impurity gases in high-molecular flexible substrates such as PET. On the one hand, there is no need to rewind the film roll substrate using a tunnel furnace before coating in the prior art, simplifying the process flow, reducing damage and pollution to the film material, and avoiding the influence of abnormal tension on subsequent processes. On the other hand, degassing by gradient heating eliminates the adsorbed gases on the base film, reduces micro-hole defects during the coating process, and dynamic tension control avoids deformation of the base film, improving the interfacial bonding force between the ITO layer and the base film and maintaining the stability of the resistance of the flexible ITO film. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 FIG. is a schematic diagram of the pre-treatment process of the substrate film roll in Embodiment 1 of the present invention.

[0016] In the figure: ① represents the film roll, and ② represents the heating system. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present invention fall within the scope of protection of the present invention.

[0018] Embodiment 1 A coating method for improving the resistance stability of a flexible ITO film includes the following steps: (1) Load the substrate film roll into the chamber of the vacuum coating equipment. Select a polyimide (PI) film roll with a thickness of 75 μm and a width of 500 mm, and adjust the vacuum degree in the chamber of the vacuum coating equipment, that is, evacuate to 4.2×10 -6 mbar; (2) Set the transmission tension to 70 N / m and the winding speed to 1.2 m / min. Unwind the substrate film roll, and adjust the temperature in the chamber of the vacuum coating equipment to heat and degas the film material. The heating and degassing are carried out in stages. The temperature in the first stage of heating is 110 °C, and the heating time is 8 min; the temperature in the second stage of heating is 140 °C, and the heating time is 7 min; (3) After degassing is completed, turn on the ITO target (In2O3:SnO2 = 90:10) during secondary winding, with a sputtering power density of 4.2 W / cm², an argon-oxygen ratio of 55:1, and a deposition thickness of 150 nm. After deposition, introduce nitrogen plasma for assisted annealing, and the annealing conditions are a temperature of 100 °C and an annealing time of 45 s.

[0019] Embodiment 2 A coating method for improving the resistance stability of flexible ITO film, comprising the following steps: (1) Load the substrate film roll into the vacuum coating equipment chamber. Select a polyimide (PI) film roll with a thickness of 50 μm and a width of 500 mm. Adjust the vacuum degree in the vacuum coating equipment chamber, that is, evacuate to 5×10 -6 mbar; (2) Set the transmission tension to 75 N / m and the winding speed to 2 m / min. Unwind the substrate film roll, and adjust the temperature in the vacuum coating equipment chamber to heat and degas the film material. The heating and degassing are carried out in stages. The temperature in the first stage of heating is 100 °C and the heating time is 10 min; the temperature in the second stage of heating is 150 °C and the heating time is 5 min; (3) After degassing is completed, turn on the ITO target (In2O3:SnO2 = 90:10) during secondary winding. The sputtering power density is 3 W / cm², the argon-oxygen ratio is 50:1, and the deposition thickness is 200 nm. After deposition is completed, introduce nitrogen plasma for assisted annealing. The annealing conditions are a temperature of 120 °C and an annealing time of 30 s.

[0020] Example 3 A coating method for improving the resistance stability of flexible ITO film, comprising the following steps: (1) Load the substrate film roll into the vacuum coating equipment chamber. Select a polyimide (PI) film roll with a thickness of 125 μm and a width of 500 mm. Adjust the vacuum degree in the vacuum coating equipment chamber, that is, evacuate to 4×10 -6 mbar; (2) Set the transmission tension to 50 N / m and the winding speed to 0.5 m / min. Unwind the substrate film roll, and adjust the temperature in the vacuum coating equipment chamber to heat and degas the film material. The heating and degassing are carried out in stages. The temperature in the first stage of heating is 120 °C and the heating time is 5 min; the temperature in the second stage of heating is 130 °C and the heating time is 10 min; (3) After degassing is completed, turn on the ITO target (In2O3:SnO2 = 90:10) during secondary winding. The sputtering power density is 5 W / cm², the argon-oxygen ratio is 60:1, and the deposition thickness is 80 nm. After deposition is completed, introduce nitrogen plasma for assisted annealing. The annealing conditions are a temperature of 80 °C and an annealing time of 60 s.

[0021] Example 4 A coating method for improving the resistance stability of flexible ITO film, comprising the following steps: (1) Load the substrate film roll into the vacuum coating equipment chamber. Select a polyethylene terephthalate (PET) film roll with a thickness of 100 μm and a width of 500 mm. Adjust the vacuum degree in the vacuum coating equipment chamber, that is, evacuate to 4.5×10-6 mbar; (2) Set the transmission tension to 100 N / m and the winding speed to 1.5 m / min. Unwind the substrate film roll, and adjust the temperature in the chamber of the vacuum coating equipment to heat and degas the film material. The heating and degassing are carried out in stages. The temperature in the first stage of heating is 115 °C, and the heating time is 7 min; the temperature in the second stage of heating is 135 °C, and the heating time is 9 min. (3) After degassing is completed, turn on the ITO target (In2O3:SnO2 = 90:10) during secondary winding. The sputtering power density is 3.5 W / cm², the argon-oxygen ratio is 65:1, and the deposition thickness is 100 nm. After deposition, introduce nitrogen plasma for assisted annealing. The annealing conditions are a temperature of 90 °C and an annealing time of 40 s.

[0022] The above are the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A coating method for improving the resistance stability of a flexible ITO film, characterized in that, It includes the following steps: (1) Load the base film roll into the vacuum coating equipment chamber and adjust the vacuum degree in the vacuum coating equipment chamber; (2) Unwind the base film roll and adjust the temperature in the vacuum coating equipment chamber to heat and degas the film material; (3) After degassing is completed, directly perform secondary winding for ITO coating operation.

2. The coating method for improving the resistance stability of the flexible ITO film according to claim 1, characterized in that, The vacuum degree in the chamber of the adjusted vacuum coating equipment is a pressure ≤ 5×10⁻ 5 mbar.

3. The coating method for improving the resistance stability of the flexible ITO film according to claim 1, wherein The transmission tension for unwinding the base roll film is 30 - 100 N / m.

4. The coating method for improving the resistance stability of the flexible ITO film according to claim 1, characterized in that, The unwinding rate of the base roll film is 0.5 - 2 m / min.

5. The coating method for improving the resistance stability of the flexible ITO film according to claim 1, characterized in that, The heating and degassing is segmented heating. The temperature in the first stage of heating is 100 - 120 °C, and the heating time is 5 - 10 min; the temperature in the second stage of heating is 130 - 150 °C, and the heating time is 5 - 10 min.

6. The coating method for improving the resistance stability of the flexible ITO film according to claim 1, wherein The subsequent ITO coating operation is to deposit an ITO layer by magnetron sputtering under the condition of maintaining a vacuum degree ≤ 5×10 -6 mbar, with a sputtering power density of 3 - 5 W / cm² and an argon-oxygen flow ratio controlled at 40:1 to 80:

1.

7. The coating method for improving the resistance stability of the flexible ITO film according to claim 6, characterized in that, The thickness of the ITO layer is 80 - 200 nm. After deposition, plasma-assisted annealing is carried out, the annealing temperature is 80 - 120 °C, and the time is 30 - 60 s.

8. The coating method for improving the resistance stability of the flexible ITO film according to claim 1, characterized in that, The base material is polyimide or polyethylene terephthalate, and the thickness is 50 - 125 μm.

9. A flexible ITO film prepared by the coating method for improving the resistance stability of the flexible ITO film according to any one of claims 1 - 8.

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