A coating method for improving the resistance stability of a flexible ITO film

Abstract

The application provides a coating method for improving the resistance stability of a flexible ITO film, and belongs to the technical field of coating, and comprises the following steps: (1) winding a base film into a vacuum coating equipment chamber, and adjusting the vacuum degree in the vacuum coating equipment chamber; (2) unwinding the base film, and adjusting the temperature in the vacuum coating equipment chamber to heat and degas the film material; and (3) directly performing secondary winding after degassing to perform ITO coating operation. The application provides a coating method for improving the resistance stability of a flexible ITO film, and realizes the stability of the resistance of the flexible ITO film through pretreatment of the base material.

Description

Technical Field

[0001] This invention relates to the field of coating technology, and more specifically to a coating method for improving the resistivity stability of flexible ITO films. Background Technology

[0002] Flexible transparent conductive films are thin films made by coating a flexible substrate with materials such as metals or oxides using physical or chemical methods. Flexible ITO films, indium tin oxide (ITO) films coated on flexible substrates, possess transparent and conductive properties, along with high conductivity, high visible light transmittance, low resistivity, high mechanical hardness, and good chemical stability. Flexible ITO films are the most commonly used thin film materials for transparent electrodes in liquid crystal displays (LCDs), plasma display panels (PDPs), electroluminescent displays (EL / OLEDs), touch panels, solar cells, and other electronic instruments.

[0003] Vacuum coating technology is a technique that deposits materials onto the surface of a substrate to form a thin film in a vacuum environment using physical or chemical methods. This technology has the advantage of being able to operate under low pressure, avoiding interference from airborne impurities and thus ensuring the purity and uniformity of the film. Vacuum coating technology has been applied to flexible ITO films. For example, patent publication CN103436844A, entitled "A Low-Temperature Deposition Apparatus and Method for ITO Film Coating on Flexible Substrate," discloses an apparatus in which a substrate winding mechanism capable of forward and reverse rotation, an ion source, and an unbalanced medium-frequency magnetron sputtering mechanism are respectively housed within a container. The ion source is located outside the unwinding assembly of the substrate winding mechanism, and the unbalanced medium-frequency magnetron sputtering mechanism is located outside the main roller of the substrate winding mechanism. A high-vacuum pumping mechanism is connected to the outside of the container, a workpiece conveying mechanism is connected to the input end of the substrate winding mechanism, and a heat exchange mechanism is connected to one end of the main roller of the substrate winding mechanism. The method involves: a workpiece conveying mechanism delivering the sample; a high-vacuum pumping mechanism evacuating the container; and a substrate winding mechanism conveying the flexible substrate, using unbalanced mid-frequency magnetron sputtering for low-temperature deposition of the flexible substrate ITO film. However, if the substrate in the above scheme is a flexible substrate, such as a PET substrate, and the substrate contains impurities such as water vapor, the release of these impurities during the coating process will contaminate the coating process and affect the resistivity 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 flexible ITO films, which achieves the stability of the resistance of flexible ITO films by pre-treating the substrate.

[0005] To achieve the above objectives, the present invention provides a coating method for improving the resistivity stability of flexible ITO films, comprising the following steps:

[0006] (1) Load the substrate film roll into the vacuum coating equipment chamber and adjust the vacuum level in the vacuum coating equipment chamber;

[0007] (2) Unwind the substrate film roll and adjust the temperature inside the vacuum coating equipment chamber to heat and degas the film material;

[0008] (3) After degassing, the ITO coating operation is carried out by direct secondary winding.

[0009] Optionally, the vacuum level in the chamber of the vacuum coating equipment is adjusted to be ≤5×10⁻. 5 mbar.

[0010] Optionally, the transmission tension of the substrate film unwinding is 30-100 N / m.

[0011] Optionally, the unwinding rate of the substrate film is 0.5-2 m / min.

[0012] Optionally, the heating and degassing is performed in stages. The temperature of the first stage of heating is 100-120℃ and the heating time is 5-10 minutes. The temperature of the second stage of heating is 130-150℃ and the heating time is 5-10 minutes.

[0013] Optionally, the subsequent ITO coating process is performed while maintaining a vacuum level ≤ 5 × 10⁻⁶. -6 Under mbar conditions, ITO layers were deposited by magnetron sputtering with a sputtering power density of 3-5 W / cm² and an argon-oxygen flow ratio of 40:1 to 80:1.

[0014] Optionally, the ITO layer has a thickness of 80-200 nm, and after deposition, it undergoes plasma-assisted annealing at a temperature of 80-120°C for 30-60 seconds.

[0015] Optionally, the substrate is polyimide or polyethylene terephthalate with a thickness of 50-125 μm.

[0016] To achieve the above objectives, the present invention also provides a flexible ITO film prepared by a coating method for improving the resistivity stability of a flexible ITO film.

[0017] The above-described technical solution of the present invention has at least the following beneficial effects:

[0018] The technical solution provided by this invention pre-treats the flexible substrate, that is, uses vacuum coating equipment to remove impurity gases from the flexible polymer substrate such as PET. On the one hand, it eliminates the need for rewinding the film roll substrate in a tunnel furnace before coating, as is done in the prior art, simplifying the process, reducing damage and contamination to the film material, and avoiding the impact of abnormal tension on subsequent processes. On the other hand, gradient heating degassing eliminates the gas adsorbed on the base film, reduces micropore defects during the coating process, and dynamic tension control avoids base film deformation, thereby 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. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the pretreatment process of the substrate film roll in Embodiment 1 of the present invention.

[0020] In the diagram: ① represents the membrane roll, and ② represents the heating system. Detailed Implementation

[0021] 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 only some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0022] Example 1

[0023] A coating method for improving the resistivity stability of flexible ITO films includes the following steps:

[0024] (1) Load the substrate film roll into the vacuum coating equipment chamber. Select a polyimide (PI) film roll with a thickness of 75 μm and a width of 500 mm. Adjust the vacuum level in the vacuum coating equipment chamber to 4.2 × 10⁻⁶. -6 mbar;

[0025] (2) Set the transmission tension to 70 N / m and the winding speed to 1.2 m / min, unwind the substrate film roll, adjust the temperature in the vacuum coating equipment chamber to heat and degas the film material. The heating and degassing is done in stages. The temperature of the first stage heating is 110℃ and the heating time is 8min; the temperature of the second stage heating is 140℃ and the heating time is 7min.

[0026] (3) After degassing, ITO target (In2O3:SnO2=90:10) is turned on during the second winding, sputtering power density is 4.2W / cm², argon-oxygen ratio is 55:1, deposition thickness is 150 nm, and nitrogen plasma is introduced for annealing after deposition. Annealing conditions are 100℃ and 45s.

[0027] Example 2

[0028] A coating method for improving the resistivity stability of flexible ITO films includes the following steps:

[0029] (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 level in the vacuum coating equipment chamber to 5 × 10⁻⁶ mm. -6 mbar;

[0030] (2) Set the transmission tension to 75 N / m and the winding speed to 2 m / min, unwind the substrate film roll, adjust the temperature in the vacuum coating equipment chamber to heat and degas the film material. The heating and degassing is done in stages. The temperature of the first stage heating is 100℃ and the heating time is 10 min; the temperature of the second stage heating is 150℃ and the heating time is 5 min.

[0031] (3) After degassing, ITO target material (In2O3:SnO2=90:10) is turned on during the second winding, sputtering power density is 3 W / cm², argon-oxygen ratio is 50:1, deposition thickness is 200 nm, and nitrogen plasma is introduced for annealing after deposition. Annealing conditions are temperature 120℃ and annealing time 30s.

[0032] Example 3

[0033] A coating method for improving the resistivity stability of flexible ITO films includes the following steps:

[0034] (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 level in the vacuum coating equipment chamber to 4 × 10⁻⁶. -6 mbar;

[0035] (2) Set the transmission tension to 50 N / m and the winding speed to 0.5 m / min, unwind the substrate film roll, adjust the temperature in the vacuum coating equipment chamber to heat and degas the film material. The heating and degassing is done in stages. The temperature of the first stage heating is 120℃ and the heating time is 5 min; the temperature of the second stage heating is 130℃ and the heating time is 10 min.

[0036] (3) After degassing, ITO target material (In2O3:SnO2=90:10) is turned on during the second winding, sputtering power density is 5 W / cm², argon-oxygen ratio is 60:1, deposition thickness is 80 nm, nitrogen plasma is introduced for annealing after deposition, annealing conditions are 80℃ and annealing time is 60s.

[0037] Example 4

[0038] A coating method for improving the resistivity stability of flexible ITO films includes the following steps:

[0039] (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 level in the vacuum coating equipment chamber to 4.5 × 10⁻⁶. -6 mbar;

[0040] (2) Set the transmission tension to 100 N / m and the winding speed to 1.5 m / min, unwind the substrate film roll, adjust the temperature in the vacuum coating equipment chamber to heat and degas the film material. The heating and degassing is done in stages. The temperature of the first stage heating is 115℃ and the heating time is 7min; the temperature of the second stage heating is 135℃ and the heating time is 9min.

[0041] (3) After degassing, ITO target (In2O3:SnO2=90:10) is turned on during the second winding, sputtering power density is 3.5W / cm², argon-oxygen ratio is 65:1, deposition thickness is 100nm, and nitrogen plasma is introduced for annealing after deposition. Annealing conditions are 90℃ and 40s.

[0042] The above are preferred embodiments of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A coating method for improving the resistivity stability of flexible ITO films, characterized in that, Includes the following steps: (1) Load the substrate film roll into the vacuum coating equipment chamber and adjust the vacuum level in the vacuum coating equipment chamber; (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; the heating and degassing is segmented heating, the temperature of the first stage heating is 100-120℃ and the heating time is 5-10min; the temperature of the second stage heating is 130-150℃ and the heating time is 5-10min. (3) After degassing, the ITO coating process is carried out by direct secondary winding; the ITO coating process is carried out while maintaining a vacuum degree ≤5×10 -6 Under mbar conditions, ITO layers were deposited by magnetron sputtering at a sputtering power density of 3-5 W / cm³. 2 The argon-oxygen flow ratio is controlled at 40:1 to 80:1, and the thickness of the ITO layer is 80-200 nm. After deposition, nitrogen plasma-assisted annealing is performed at a temperature of 80-120℃ for 30-60 seconds.

2. The coating method for improving the resistivity stability of flexible ITO films according to claim 1, characterized in that, The vacuum level inside the vacuum coating equipment chamber is adjusted to be ≤5×10. - 5 mbar.

3. The coating method for improving the resistivity stability of flexible ITO films according to claim 1, characterized in that, The transmission tension of the substrate film unwinding is 30-100 N / m.

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

5. The coating method for improving the resistivity stability of flexible ITO films according to claim 1, characterized in that, The substrate is polyimide or polyethylene terephthalate with a thickness of 50-125 μm.

6. A flexible ITO film prepared by a coating method for improving the resistivity stability of a flexible ITO film as described in any one of claims 1-5.

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