A method for producing a high-density and high-conductivity metallized Al film on a flexible organic-based film

Abstract

The application provides a method for preparing a high-density and high-conductivity metallized Al film on a flexible organic base film, which comprises the following steps: performing radio frequency capacitive coupling plasma pretreatment on a 20-100 mu m flexible organic film as a base film; and depositing an Al film on the pretreated base film by using resistance evaporation technology, wherein Ar gas is introduced as a pretreatment gas, ionized Ar ions have etching effect on the base film but do not cause thermal damage to the base film, and then a suitable evaporation coating process is adopted, so that the method has the dual effects of physical etching and chemical modification on the 20-100 mu m flexible organic base film without damaging the flexible organic base film, and a high-density, high-conductivity metallized Al film is prepared.

Description

Technical Field

[0001] This invention relates to the field of surface treatment technology, and more specifically to a method for preparing a high-density and high-conductivity metallized Al film on a flexible organic substrate film. Background Technology

[0002] With the continuous advancement of technology, metallized thin films have been widely used in numerous fields, including electronic devices, optical devices, and sensors. Metallized thin films are typically deposited onto flexible substrates (PP, PI, PET, etc.) using physical vapor deposition techniques, such as vacuum evaporation and magnetron sputtering, to deposit metals (Au, Ag, Cu, Al, Zn, etc.). Because organic polymer substrates have low surface energy while metal particles have high surface energy, metal particles tend to grow in island-like formations on polymer surfaces. Combined with the thin film thickness (generally less than 100 nm) and rapid deposition rate, the density of the metallized thin film is difficult to guarantee, severely impacting its performance. For example, in electronic devices, metallized thin films in micro-sensors are mainly used to form conductive paths. Due to insufficient metal layer density, current leakage is highly likely, leading to performance degradation or failure of the micro-sensor. In the field of optical devices, metallized thin films are often used to achieve specific reflective functions. Because of the non-dense microstructure of thin films, defects such as micropores or cracks may exist within the film, causing energy loss due to scattering and absorption of incident light, thus reducing the film's optical performance. In the field of sensors, metallized thin films can be fabricated as sensitive electrodes for signal detection and transmission. Non-dense films allow interference to enter the film, hindering effective interaction between the sensor and the analyte, thereby reducing the sensor's sensitivity and accuracy. For metallized Al films, they are often used as conductive electrodes in thin-film capacitors. At the same resistivity, continuous and dense films can accommodate larger currents, and their thinner thickness results in better self-healing properties. Furthermore, metallized Al films are often used as reflective and electrode layers in solar cells to improve their light absorption efficiency and current transmission capacity. Non-dense metallized Al films are prone to oxidation or corrosion, leading to film failure and degradation, thus reducing battery life. In summary, improving the density of metallized thin films is crucial, directly affecting their optical, electrical, and environmental adaptability properties.

[0003] Glow plasma pretreatment is a common surface treatment technique widely used in physical vapor deposition (PVD). When preparing mechanical or functional thin films using magnetron sputtering, arc ion plating, or other vacuum deposition techniques, glow plasma is typically used to pretreat flexible or rigid substrates before depositing metal or ceramic films. For example, Chinese invention patent CN202211672969.4 discloses a nano-multilayer corrosion-resistant coating and its preparation method for a lightweight alloy component. This invention uses glow discharge plasma technology to "etch" the substrate surface. To effectively remove contaminants from the metal substrate surface while achieving micro-etching of the substrate, the inventors use a high voltage of 2000–2400V and a processing time of 30–45 minutes. This pretreatment method uses strong plasma energy and has a long processing time, making it only suitable for alloy substrates. When applied to flexible organic substrates, it easily burns the flexible organic substrate; therefore, this process is unsuitable for treating the surface of flexible organic substrates.

[0004] Remote plasma technology involves delivering gas to a specific device, then using an electric or magnetic field to generate plasma, which is then transmitted to the surface area requiring treatment. Because the remote plasma source does not directly contact the surface to be treated, but generates plasma at a certain distance, the plasma energy is lower, making it less prone to thermal and chemical damage. This makes it suitable for pretreatment of thin, flexible organic substrates.

[0005] For example, Chinese invention patent CN202111491280.7 discloses a method for improving the nucleation uniformity of metallized thin films on organic substrates. This invention targets flexible organic polymer substrates with a thickness of 3–15 μm and employs remote plasma pretreatment technology to pretreat the organic thin film by ionizing air. However, the remote plasma technology in this invention can only achieve pretreatment of the surface of flexible organic polymer substrates with a thickness of less than 15 μm. During this remote plasma pretreatment process, the main oxygen and nitrogen gases in the air have relatively light atomic masses and are less likely to damage the substrate film. They can also form N- or O-containing functional groups on the substrate film surface, thereby increasing the nucleation density of the metallized thin film and thus facilitating the formation of a dense metallized thin film.

[0006] When the thickness of the flexible organic polymer substrate is greater than 20 μm, the etching effect on the substrate film is limited due to the low energy of the remote plasma, resulting in unsatisfactory pretreatment effects. However, no methods have been reported for plasma pretreatment of flexible organic thin films with a thickness greater than 20 μm to improve film density and conductivity.

[0007] Therefore, developing a processing technology for flexible organic thin films larger than 20 μm to improve film density and conductivity is an urgent problem to be solved. Summary of the Invention

[0008] This invention addresses the problem of poor density and conductivity of metal films caused by imperfect base film processing technology for flexible organic thin films with a thickness of 20–100 μm.

[0009] To achieve the above objectives, the present invention provides a method for preparing a high-density and high-conductivity metallized Al film on a flexible organic substrate, comprising the following steps:

[0010] S1: A flexible organic film with a thickness of 20-100 μm is selected as the base film;

[0011] S2: The base film is ultrasonically cleaned sequentially with anhydrous ethanol and deionized water. The ultrasonic cleaning time for both anhydrous ethanol and deionized water is 1-3 min. Then, it is dried at 60℃ for later use.

[0012] S3: Fix the dried and ready-to-use base film onto the substrate stage and perform radio frequency capacitive coupling plasma pretreatment on the base film;

[0013] S4: By using resistance evaporation technology to deposit an Al film on the pretreated base film, a high-density and high-conductivity metallized Al film can be obtained.

[0014] Furthermore, the gas used in the radio frequency capacitive coupling plasma pretreatment in step S3 is Ar gas with a purity of 99.999%.

[0015] Furthermore, the process parameters for resistive evaporation in step S4 are: background vacuum degree ≤ 8.4 × 10⁻⁶. -4 Preferably 7×10 -4 Pa; substrate stage temperature ≤15℃, evaporation rate Preferred

[0016] Furthermore, the process parameters for the radio frequency capacitively coupled plasma pretreatment in step S3 are: processing power of 30-50W, processing gas pressure of 0.5-5Pa, and processing time of 2-5min.

[0017] Further, step S3 specifically involves laying the dried and prepared base film flat on the sample stage, fixing it with high-temperature tape, and then placing the base film in a capacitively coupled radio frequency glow plasma pretreatment device for radio frequency capacitively coupled plasma pretreatment.

[0018] Furthermore, the specific steps of step S3, which involves placing the base film in a capacitively coupled radio frequency glow discharge plasma pretreatment device for radio frequency capacitively coupled plasma pretreatment, are as follows:

[0019] S31: Place the base film in a capacitively coupled radio frequency glow plasma pretreatment device;

[0020] S32: Close the chamber door and use both a mechanical pump and a molecular pump to evacuate the chamber to a vacuum level of ≤2.8×10⁻⁶. -3 Pa;

[0021] S33: Open the gas cylinder and introduce Ar gas with a purity of 99.999% to stabilize the gas pressure at 0.5-5 Pa;

[0022] S34: Set the RF power supply to 30-50W, turn on the power to generate glow plasma, and treat the flexible substrate film for 2-5 minutes.

[0023] S35: After the pretreatment is completed, turn off the radio frequency power supply, the inlet valve, the molecular pump and the mechanical pump in sequence; after the mechanical pump stops rotating, open the vent valve, and after the chamber pressure rises to atmospheric pressure, open the chamber and take out the flexible base film to obtain the thin film of radio frequency capacitively coupled plasma pretreatment.

[0024] Furthermore, the specific steps in step S4 for depositing an Al film on the pretreated base film using resistance evaporation technology are as follows:

[0025] S41: Place the pretreated flexible base film in the evaporation coating equipment and fix it to the substrate stage with high-temperature tape;

[0026] S42: Place the Al particles into the evaporation boat and close the hatch; sequentially use a mechanical pump and a molecular pump to evacuate the chamber to a vacuum of 7 × 10⁻⁶. -4 Pa is below; Al particles are cylindrical, with a diameter and length of 1–3 mm;

[0027] S43: Turn on the evaporation source and use a film thickness gauge to control the evaporation rate. Set the substrate stage temperature to ≤15℃;

[0028] S44: Once the set film thickness is reached, the evaporation process ends, and the evaporation source is turned off;

[0029] S45: Sequentially turn off the molecular pump and the mechanical pump. After the chamber temperature drops to room temperature, open the vent valve to prepare a high-density and high-conductivity metallized Al film on the flexible substrate.

[0030] Furthermore, the film thickness in S44 is 10-100 nm;

[0031] Furthermore, in order to make the deposited Al film more uniform, the substrate stage rotation speed is 5 r / min in step S43.

[0032] Furthermore, the flexible organic film is selected from one of PP, PET, and PI.

[0033] This invention employs radio frequency capacitively coupled plasma pretreatment technology. A certain amount of gas molecules are introduced between two electrodes, and a high-frequency electric field is generated by a radio frequency power supply to excite the gas molecules to ionize, thereby generating plasma. Since the sample to be processed is placed on or between the electrodes, the plasma directly acts on the sample surface. The plasma density is relatively high, and the plasma energy is stronger than that of remote plasma, which can achieve a better physical etching effect on flexible organic thick films. At the same time, by reasonably controlling parameters such as power and time, thermal damage to the substrate film surface is prevented.

[0034] The pretreatment gas used in this invention is Ar gas. Compared to air, Ar has a larger atomic radius and mass, resulting in a stronger physical etching effect on the base film. This is more effective in breaking the C-C and CH bonds in the PP film, thereby increasing the surface energy of the base film. Furthermore, although the plasma pretreatment gas does not contain elements such as O and N, a certain number of polar functional groups such as CO / CN and OC=O can still be formed on the surface of the PP base film after Ar treatment. This is because the Ar plasma breaks the C-C and CH bonds on the PP base film surface, forming C-dangling bonds, which enhances surface activity. These C-dangling bonds can, on the one hand, form O- or N-containing polar functional groups with residual air molecules in the cavity; on the other hand, when the PP base film is removed from the cavity and exposed to the atmospheric environment, the highly reactive C-dangling bonds can further react chemically with O or N in the atmosphere to form polar functional groups. Therefore, when using Ar plasma pretreatment to pretreat the PP base film, in addition to its strong physical etching effect, it can also have a chemical modification effect similar to that of air plasma, thus achieving a better surface treatment effect.

[0035] Beneficial effects:

[0036] 1. This invention introduces Ar gas as a pretreatment gas and combines it with capacitively coupled radio frequency plasma (CRF) pretreatment technology to pretreat flexible organic substrate films of 20–100 μm. Due to the large atomic mass of Ar gas and the high energy of CRF, the ionized Ar ions have an etching effect on the substrate film without causing thermal damage. Therefore, for flexible organic substrate films of 20–100 μm, this method can help increase the nucleation density of deposited particles on the substrate film, reduce the film thickness threshold, improve the compactness of the metal film, thereby reducing the scattering effect of the metal film on electrons and improving the conductivity of the thin film.

[0037] 2. This invention employs capacitively coupled radio frequency plasma pretreatment technology to pretreat flexible organic substrate films with a thickness of 20–100 μm. The gas used in the pretreatment is Ar. Then, by adopting a suitable evaporation deposition process, this method can achieve both physical etching and chemical modification of flexible organic substrate films with a thickness of 20–100 μm without damaging the flexible organic substrate film, thereby improving the surface free energy of the flexible organic substrate film. In addition, by reasonably controlling the evaporation deposition process, the metal Al film deposited on the flexible organic substrate film has a low film-forming threshold thickness and significantly improved surface density, ultimately improving the electrical properties of the Al film and preparing a metallized Al film with high density and high conductivity.

[0038] 3. The present invention employs capacitive coupling radio frequency plasma pretreatment technology to pretreat flexible organic base films of 20–100 μm, which is beneficial to increase the nucleation density of particles, reduce the threshold thickness of film formation, improve the compactness of the film, thereby reducing the scattering effect of the film on electrons and improving the conductivity of the film. Attached Figure Description

[0039] Figure 1 The variation law of static water contact angle of PP base film under different plasma pretreatment conditions;

[0040] Figure 2 The variation of sheet resistance of Al film with evaporation process: (a) evaporation rate; (b) substrate stage temperature; (c) background vacuum;

[0041] Figure 3 The variation of sheet resistance of Al film with and without plasma pretreatment under the following conditions: (a) evaporation rate; (b) substrate stage temperature; (c) background vacuum;

[0042] Figure 4 AFM morphology of Al film surface on PP base film, (a) PP base film pretreated with Ar gas; (b) untreated PP base film;

[0043] Figure 5 SEM morphology of Al films of different thicknesses on untreated PP base film: (a) 1 nm; (b) 3 nm; (c) 5 nm;

[0044] Figure 6 SEM morphology of Al films of different thicknesses on PP base film after Ar pretreatment: (a) 1 nm; (b) 3 nm; (c) 5 nm;

[0045] Figure 7 Figure 1.1 in Example 1 shows the PP base film shrinking due to overheating when the processing power is greater than 50W. Detailed Implementation

[0046] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0047] The technical solution of the present invention will be further explained below with reference to implementation examples.

[0048] Example 1

[0049] In this embodiment, a PP base film with a thickness of 47 μm was selected, and the hydrophilicity of the PP base film surface under different plasma pretreatment processes was studied.

[0050] 1.1 Effect of different processing power on the hydrophilic properties of PP base film

[0051] (1) Place a flexible organic PP film with a thickness of 47μm in an ultrasonic cleaning device and clean it with anhydrous ethanol and deionized water in sequence for 2min each time; dry it at 60℃ for later use.

[0052] (2) Lay the dried and ready-to-use base film flat on the sample stage and fix it with high temperature tape. The distance between the two plates is 69 mm.

[0053] (3) The base film is placed in a capacitively coupled radio frequency glow plasma pretreatment device;

[0054] (4) Close the chamber door and use a mechanical pump and a molecular pump to evacuate the chamber to a vacuum of 2.8 × 10⁻⁶. -3 Pa;

[0055] (5) Open the gas cylinder and introduce Ar gas with a purity of 99.999% to stabilize the gas pressure at 1 Pa;

[0056] (6) Set the RF power supply to 30W, 40W, and 50W, turn on the power, generate glow plasma, and treat the flexible base film for 2 minutes.

[0057] (7) After the pretreatment is completed, turn off the radio frequency power supply, the inlet valve, the molecular pump and the mechanical pump in sequence; after the mechanical pump stops rotating, open the vent valve, and after the chamber pressure rises to normal pressure, open the chamber and take out the flexible base film to obtain the thin film of radio frequency capacitive coupling plasma pretreatment.

[0058] like Figure 1 As shown in (a), with the increase of processing power, the static water contact angle of the PP base film decreases, and the hydrophilicity of the base film increases. The hydrophilicity of the film is better when the processing power is 30-50W. When the processing power is further increased, the PP base film shrinks due to overheating.

[0059] A smaller static water contact angle indicates better hydrophilicity of the base film, higher surface free energy, and greater activity. When the processing power exceeds 50W, the film undergoes wrinkling, resulting in an uneven surface. Figure 7 As shown, the static water contact angle cannot be measured under this wrinkled state.

[0060] 1.2 Effect of different treatment times on the hydrophilicity of PP base film

[0061] The processing method is described in 1.1, where the RF power supply is set to 40W and the processing time is 1min, 2min, 4min, and 5min.

[0062] Depend on Figure 1 (b) It can be seen that when the treatment time is 2 to 5 minutes, the static water contact angle of the base film is relatively small. If the treatment time is too short, the expected effect will not be achieved. If the treatment time exceeds 5 minutes, the PP base film will wrinkle due to temperature rise, the surface will be uneven, and the static water contact angle cannot be measured.

[0063] 1.3 Effect of different processing air pressures on the hydrophilicity of PP base film

[0064] The treatment method is as described in 1.1, wherein the radio frequency power is set to 40W, the flexible substrate is treated for 4 minutes, and the treatment pressure is set to 0.5Pa, 1Pa, 2Pa, 3Pa, and 5Pa.

[0065] Depend on Figure 1 (c) It can be seen that the processing pressure has little effect on the hydrophilicity of the PP base membrane. Within a wide range of 0.5–5 Pa, the PP base membrane exhibits good hydrophilicity. When the processing pressure is greater than 5 Pa, the molecular pump in the vacuum system is subjected to a large load, which can easily damage the molecular pump.

[0066] 1.4 Effect of different treatment gases on the hydrophilicity of PP base film

[0067] The treatment method is as described in 1.1, wherein the RF power supply is set to 40W, the flexible substrate is treated for 4 minutes, and the treatment gas is high-purity Ar, pure O2, or a mixture of Ar and O2 with a gas flow rate ratio of 1:1.

[0068] Depend on Figure 1 (d) It can be seen that, compared with pure O2 or Ar+O2 mixed gas, the static water contact angle on the base film surface is the smallest after plasma pretreatment with high-purity Ar gas, indicating that its pretreatment effect is the best.

[0069] Table 1 shows the relative strength of chemical bonds on the surface of PP base films before and after pretreatment. As can be seen from the table, CO / CN, OC=O, and C=O / NC=O polar functional groups were generated on the surface of the PP base films after treatment with three different gases. CC / CH bonds are inherent chemical bonds in the PP base films; a decrease in CC / CH bond content corresponds to an increase in the content of polar functional groups. Table 1 also shows that the surface polar functional group content is highest after treatment with Ar:O2 = 1:1, followed by pure Ar, and lowest after treatment with pure O2. Although Ar plasma does not contain elements such as O and N, a certain number of polar functional groups such as CO / CN and OC=O can still form on the surface of the PP base film. This is mainly because after Ar plasma pretreatment, the C-C bonds and CH bonds on the surface of the PP base film are broken, forming C-dangling bonds. These dangling bonds are highly chemically reactive and can form functional groups with residual air molecules in the vacuum chamber, or when the PP base film is removed from the chamber and exposed to the atmosphere, the C-dangling bonds continue to react chemically with O and N elements in the atmosphere to form polar functional groups. Furthermore, it is worth noting that the content of polar functional groups on the surface of the PP base film after O2 plasma pretreatment is the lowest. This is because, compared to Ar atoms, O atoms have a smaller radius and lighter mass, making it more difficult to break C-C bonds or CH bonds, resulting in fewer C-dangling bonds and thus a lower content of polar functional groups.

[0070] Table 1. Relative strength of chemical bonds on the surface of PP base film before and after pretreatment.

[0071]

[0072] Furthermore, the surface roughness of the PP base film before and after pretreatment was tested using a Bruker Icon atomic force microscope (AFM). After plasma pretreatment, the surface of the PP base film changed from the original fibrous morphology to a fine granular morphology. The roughness Ra of the PP base film after Ar plasma pretreatment was 1.58 nm, the roughness Ra after Ar:O2 = 1:1 plasma pretreatment was 3.92 nm, and the roughness Ra after O2 plasma pretreatment was 4.24 nm. The surface roughness Ra of the untreated base film was 3.79 nm. The comparison shows that the surface roughness of the base film decreased after Ar plasma pretreatment, while the roughness of the base film after pretreatment with the other two gases did not change much.

[0073] The hydrophilicity of the base film is closely related to its surface chemical composition and roughness. Specifically, surface hydrophilicity is related to two aspects: first, the content of surface polar functional groups; a higher content of these groups results in stronger hydrophilicity. Second, the surface morphology and roughness; generally, a suitable surface morphology and lower roughness are beneficial to the hydrophilicity of the PP base film. Although the content of surface polar functional groups in the PP base film pretreated with Ar plasma is lower than that in the base film pretreated with Ar:O2 = 1:1 plasma, its surface morphology shows even lower surface roughness. In summary, under the combined effect of physical etching and chemical modification, the PP base film pretreated with Ar plasma exhibits the best hydrophilicity, indicating that it has the highest surface free energy and the greatest surface activity.

[0074] Example 2

[0075] This embodiment studies the influence of the vapor deposition process on the electrical properties of Al films, such as... Figure 2 As shown, the base film used in this embodiment is an untreated PP base film.

[0076] 2.1 Effect of Evaporation Rate on the Electrical Properties of Al Films

[0077] The specific method is as follows:

[0078] (1) Place the untreated PP base film with a thickness of 47μm in the evaporation coating equipment and fix it to the substrate stage with high temperature tape; the distance between the two plates is 69mm;

[0079] (2) Place cylindrical Al particles with a length and diameter of 2 mm into the evaporation boat and close the hatch; use a mechanical pump and a molecular pump sequentially to evacuate the chamber to a vacuum of 8.5 × 10⁻⁶. -4 Pa, meaning the cavity's base vacuum level is 8.5 × 10⁻⁶. -4 Pa;

[0080] (3) Turn on the evaporation source and use a film thickness gauge to control the evaporation rate. Set the substrate stage temperature to 5℃ and the substrate stage rotation speed to 5r / min;

[0081] (4) When the Al film thickness reaches 20 nm, the evaporation process ends and the evaporation source is turned off;

[0082] (5) After turning off the molecular pump and mechanical pump in sequence and waiting for the chamber temperature to drop to room temperature, open the vent valve to prepare a metallized Al film on the flexible base film.

[0083] Depend on Figure 2 (a) It can be seen that when the deposition rate increases from... Rise to At this point, the sheet resistance of the Al film decreased significantly, indicating a significant improvement in its electrical properties. The improved conductivity of the Al film stems from the increased film density, which reduces electron scattering. When the deposition rate increases from... Continue to increase to Its electrical properties do not change significantly. However, when the deposition rate is further increased, the PP base film is prone to burns and shrinkage.

[0084] 2.2 Effect of substrate stage temperature on the electrical properties of Al films

[0085] The processing method is described in section 2.1, where the deposition rate is set to... The substrate stage temperature is set to 5 degrees, 15 degrees, and 25 degrees.

[0086] Depend on Figure 2 (b) It can be seen that the electrical properties of the film deteriorate significantly when the substrate stage temperature increases from 15 degrees to 25 degrees. Therefore, in order to obtain a film with excellent electrical properties and ensure that the PP base film is not burned, the substrate stage temperature should be kept ≤15 degrees.

[0087] 2.3 Influence of cavity background vacuum on the electrical properties of Al films

[0088] The processing method is described in section 2.1, where the deposition rate is set to... The cavity's base vacuum level is set to 2.0 × 10⁻⁶. -3 Pa, 1.0×10 -3 Pa, 8.5 × 10 -4 Pa, 7×10 -4 Pa, 6×10 -4 Pa, 2.5 × 10 -4 Pa.

[0089] like Figure 2 As shown in (c). When the cavity's base vacuum is ≤7×10 -4 At a pressure of Pa, the sheet resistance of the Al film decreases significantly. This is because as the background vacuum level increases, the residual O2 content in the cavity decreases, and the content of O atoms as impurities in the Al film decreases. Since O impurities in the film can react chemically with Al to form amorphous Al2O3 with extremely high resistivity, this deteriorates the electrical properties of the film.

[0090] Example 3

[0091] 3.1 Effect of evaporation rate on the change of sheet resistance of Al film with and without plasma pretreatment

[0092] ①The effect of evaporation rate on the change of sheet resistance of Al film under plasma pretreatment conditions is shown in the following specific implementation method:

[0093] (1) Place a flexible organic PP film with a thickness of 47μm in an ultrasonic cleaning device and clean it with anhydrous ethanol and deionized water in sequence for 2min each time; dry it at 60℃ for later use.

[0094] (2) Lay the dried and ready-to-use base film flat on the sample stage and fix it with high temperature tape. The distance between the two plates is 69 mm.

[0095] (3) The base film is placed in a capacitively coupled radio frequency glow plasma pretreatment device;

[0096] (4) Close the chamber door and use a mechanical pump and a molecular pump to evacuate the chamber to a vacuum of 2.8 × 10⁻⁶. -3 Pa;

[0097] (5) Open the gas cylinder and introduce Ar gas with a purity of 99.999% at a treatment pressure of 1 Pa;

[0098] (6) Set the RF power supply to 40W, turn on the power, generate glow plasma, and treat the flexible substrate film for 4 minutes.

[0099] (7) After the pretreatment is completed, turn off the radio frequency power supply, the inlet valve, the molecular pump and the mechanical pump in sequence; after the mechanical pump stops rotating, open the vent valve, and after the chamber pressure rises to atmospheric pressure, open the chamber and take out the flexible base film to obtain the radio frequency capacitively coupled plasma pretreatment film.

[0100] (8) Place the pretreated PP base film in the evaporation coating equipment and fix it to the substrate stage with high temperature tape;

[0101] (9) Place cylindrical Al particles with a length and diameter of 2 mm into the evaporation boat and close the hatch; use a mechanical pump and a molecular pump sequentially to evacuate the chamber to a vacuum of 8.5 × 10⁻⁶. -4 Pa, meaning the cavity's base vacuum level is 8.5 × 10⁻⁶. -4 Pa;

[0102] (10) Turn on the evaporation source and use a film thickness gauge to control the evaporation rate. Set the substrate stage temperature to 5℃ and the substrate stage rotation speed to 5r / min;

[0103] (11) When the Al film thickness reaches 20 nm, the evaporation process ends and the evaporation source is turned off;

[0104] (12) After turning off the molecular pump and mechanical pump in sequence, and waiting for the chamber temperature to drop to room temperature, open the vent valve to prepare a metallized Al film on the flexible base film.

[0105] The effect of deposition rate on Al film sheet resistance under these process conditions is shown in [reference needed]. Figure 3(a) Black curve.

[0106] ② The effect of evaporation rate on the change of Al film sheet resistance under plasma-free pretreatment conditions is described in detail in Example 2, Section 2.1. The effect of deposition rate on the change of Al film sheet resistance under these conditions is explained in [link to example]. Figure 3 (a) Red curve.

[0107] 3.2 Effect of substrate stage temperature on the sheet resistance of Al film with and without plasma pretreatment

[0108] ① The effect of substrate stage temperature on the sheet resistance of Al film under plasma pretreatment conditions is described in section 3.1, ①, where the evaporation rate is set to... The effect of substrate stage temperature on the sheet resistance of Al film was investigated under the following process conditions: 5℃, 15℃, and 25℃. Figure 3 (b) Black curve.

[0109] ② The effect of substrate stage temperature on the sheet resistance of Al film under plasma-free pretreatment conditions. For specific implementation methods, please refer to ② in 3.1, where the evaporation rate is set to... The effect of substrate stage temperature on the sheet resistance of Al film was investigated under the following process conditions: 5℃, 15℃, and 25℃. Figure 3 (b) Red curve.

[0110] 3.3 Effect of cavity background vacuum on Al film sheet resistance variation with and without plasma pretreatment

[0111] ① The effect of the cavity's base vacuum on the change in Al film sheet resistance under plasma pretreatment conditions is explained in section 3.1, ①, where the evaporation rate is set to... The cavity's base vacuum level is set to 2.0 × 10⁻⁶. -3 Pa, 1.0×10 -3 Pa, 8.5 × 10 -4 Pa, 7×10 -4 Pa, 6×10 -4 Pa, 2.5 × 10 -4 Pa.

[0112] The effect of substrate stage temperature on the sheet resistance of Al film under the process conditions is shown in [reference needed]. Figure 3 (c) Black curve.

[0113] ② The effect of substrate stage temperature on the sheet resistance of Al film under plasma-free pretreatment conditions. For specific implementation methods, please refer to ② in 3.1, where the evaporation rate is set to... The cavity's base vacuum level is set to 2.0 × 10⁻⁶. -3 Pa, 1.0×10 -3 Pa, 8.5×10 -4 Pa, 7×10 -4 Pa, 6×10 -4 Pa, 2.5 × 10 -4 Pa.

[0114] The effect of substrate stage temperature on the sheet resistance of Al film under the process conditions is shown in [reference needed]. Figure 3 (c) Red curve.

[0115] Depend on Figure 3 It can be seen that, under various evaporation process conditions, the sheet resistance of the Al film deposited on the PP base film after Ar plasma pretreatment is significantly lower than that of the Al film on the untreated PP film. This indicates that using plasma pretreatment process for PP base film and then evaporating Al film on it can significantly improve its conductivity.

[0116] Further, Al films with a thickness of 20 nm were deposited on both Ar plasma-pretreated PP films and untreated PP films, with an evaporation rate of [missing information]. The substrate stage temperature was 5℃, and the cavity floor vacuum was evacuated to 8.5×10⁻⁶. -4 Pa, its AFM morphology is as follows Figure 6 As shown in the figure, the Al films prepared under both process conditions exhibit a granular morphology, but the Al film pretreated with Ar plasma has a finer particle size and a denser film. Therefore, Ar plasma pretreatment of the base film helps to form a high-density Al film, thereby improving the electrical properties of the film.

[0117] Example 4

[0118] In this embodiment, Al thin films were deposited on both untreated PP substrate films and PP substrate films pretreated with Ar plasma using the same vapor deposition process.

[0119] The process for depositing an Al thin film on a PP substrate film pretreated with Ar plasma is described in 3.1① of Example 3, and the process for depositing an Al thin film on an untreated PP substrate film is described in 3.1② of Example 3; the evaporation rate is set to... The background vacuum level is 7.0 × 10⁻⁶. -4 Pa. Simultaneously, the film thickness was monitored in real-time using a film thickness gauge; the surface morphology of the deposited Al film was observed using a cold field scanning electron microscope (SEM) to capture the nucleation and growth process of the film. Comparison Figure 5 and Figure 6 It can be seen that,

[0120] When the film thickness is 1 nm, the Al layer deposited under both conditions is not fully formed, and isolated nanoclusters can be observed. However, after Ar plasma pretreatment, the Al film deposited on the PP film has a higher nucleation density, such as... Figure 6 As shown in (a), when the film thickness is 3 nm, the Al layer prepared on the untreated PP still does not form a continuous film, and isolated island structures can still be observed, while the Al layer deposited on the pretreated PP has basically formed a continuous film. When the film thickness is further increased to 5 nm, the Al layer on the untreated PP has basically formed a continuous film, but microscopic pores and gaps can still be seen at the merging points of the islands. It can be seen that the introduction of base film plasma pretreatment process can improve the nucleation density of Al nanoparticles, reduce the film formation threshold thickness, and thus prepare continuous and dense metallized films.

[0121] The two embodiments described above are merely some specific implementations of the present invention. For those skilled in the art, appropriate adjustments and modifications can be made to the selection of raw materials, screening of concentration ranges, and setting of molar ratios without departing from the principles of the present invention, and these modifications all fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-density and high-conductivity metallized Al film on a flexible organic substrate, characterized in that, Includes the following steps: S1: A flexible organic film with a thickness of 20–100 μm is selected as the base film; S2: The base film is ultrasonically cleaned sequentially with anhydrous ethanol and deionized water. The ultrasonic cleaning time for both anhydrous ethanol and deionized water is 1-3 min. Then, it is dried at 60℃ for later use. S3: Fix the dried and ready-to-use base film onto the substrate stage and perform radio frequency capacitive coupling plasma pretreatment on the base film; S4: High-density and high-conductivity metallized Al films can be obtained by depositing Al films on pretreated base films using resistance evaporation technology. The gas used in the radio frequency capacitive coupling plasma pretreatment in step S3 is Ar gas with a purity of 99.999%. The process parameters for resistive evaporation in step S4 are: background vacuum degree ≤ 7 × 10⁻⁶ -4 Pa; The substrate stage temperature is ≤15℃, and the evaporation rate is 0.5~2.5 Å / s; The process parameters for the radio frequency capacitively coupled plasma pretreatment in step S3 are: processing power of 30~50 W, processing gas pressure of 0.5~5 Pa, and processing time of 2~5 min.

2. The method for preparing a high-density and high-conductivity metallized Al film on a flexible organic substrate film according to claim 1, characterized in that, Step S3 specifically involves laying the dried and prepared base film flat on the sample stage, fixing it with high-temperature tape, and then placing the base film in a capacitively coupled radio frequency glow plasma pretreatment device for radio frequency capacitively coupled plasma pretreatment.

3. The method for preparing a high-density and high-conductivity metallized Al film on a flexible organic substrate film according to claim 2, characterized in that, Step S3, which involves placing the base film in a capacitively coupled radio frequency glow discharge plasma pretreatment device for radio frequency capacitively coupled plasma pretreatment, comprises the following steps: S31: Place the base film in a capacitively coupled radio frequency glow plasma pretreatment device; S32: Close the chamber door and use both a mechanical pump and a molecular pump to evacuate the chamber to a vacuum level of ≤2.8×10⁻⁶. -3 Pa; S33: Open the gas cylinder and introduce Ar gas with a purity of 99.999% to stabilize the gas pressure at 0.5-5 Pa; S34: Set the RF power supply to 30-50 W, turn on the power to generate glow plasma, and treat the flexible substrate film for 2-5 minutes. S35: After the pretreatment is completed, turn off the radio frequency power supply, the inlet valve, the molecular pump and the mechanical pump in sequence; after the mechanical pump stops rotating, open the vent valve, and after the chamber pressure rises to atmospheric pressure, open the chamber and take out the flexible base film to obtain the thin film of radio frequency capacitively coupled plasma pretreatment.

4. The method for preparing a high-density and high-conductivity metallized Al film on a flexible organic substrate film according to claim 1, characterized in that, The specific steps in step S4 for depositing an Al film on the pretreated base film using resistance evaporation technology are as follows: S41: Place the pretreated flexible base film in the evaporation coating equipment and fix it to the substrate stage with high-temperature tape; S42: Place the Al particles into the evaporation boat and close the hatch; sequentially use a mechanical pump and a molecular pump to evacuate the chamber to a vacuum of 7 × 10⁻⁶. -4 Below Pa; S43: Turn on the evaporation source, use a film thickness gauge to control the evaporation rate to 0.5~2.5 Å / s, and set the substrate stage temperature to ≤15℃; S44: Once the set film thickness is reached, the evaporation process ends, and the evaporation source is turned off; S45: Sequentially turn off the molecular pump and the mechanical pump. After the chamber temperature drops to room temperature, open the vent valve to prepare a high-density and high-conductivity metallized Al film on the flexible substrate.

5. The method for preparing a high-density and high-conductivity metallized Al film on a flexible organic substrate film according to claim 4, characterized in that, In step S43, the substrate stage rotation speed is 5 r / min.

6. The method for preparing a high-density and high-conductivity metallized Al film on a flexible organic substrate film according to claim 1, characterized in that, The flexible organic film is selected from PP, PET, and PI.

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