Preparation method of high-performance PFA film for chip

Abstract

The invention relates to the technical field of high polymer materials, and discloses a preparation method of a high-performance PFA film for a chip, and the composition comprises the following solid components: PFA resin, a multifunctional fluorinated organosilane cross-linking agent and a photoinitiator. The molecular structure of the cross-linking agent simultaneously contains hydrolysable silane groups capable of forming covalent bonds with a substrate, and photosensitive functional groups capable of polymerizing under the action of ultraviolet light. The preparation method comprises the following steps: coating a substrate with the composition, and sequentially carrying out curing steps of low-temperature pre-baking, ultraviolet exposure and low-temperature post-baking. By introducing the specific difunctional cross-linking agent and adopting a low-temperature photocuring process, the technical problems that the traditional PFA film forming temperature is high and the adhesive force with a substrate is poor are solved. According to the method, chemical crosslinking in the PFA film layer and chemical bonding of a film layer-substrate interface can be achieved under the low-temperature condition, and the obtained PFA film has excellent adhesive strength and solvent resistance and can be applied to the field of thermosensitive electronic devices.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a method for preparing a high-performance PFA film for chips. Background Technology

[0002] Perfluoroalkoxy alkane (PFA), as a type of perfluoropolymer, possesses excellent chemical inertness, outstanding thermal stability, low dielectric constant, and low surface energy, making it a key candidate material in fields such as microelectronics, semiconductor manufacturing, anti-corrosion coatings, and biomedicine. It is particularly suitable for preparing high-performance protective films or dielectric layers.

[0003] However, traditional methods for applying PFA resin to substrates to form thin films have inherent technical bottlenecks. PFA itself has an extremely high melting temperature, typically requiring melting processes at temperatures above 300°C to form a film. Such stringent high-temperature conditions severely limit its application on heat-sensitive substrates, such as many polymer substrates or wafers with integrated electronic components, which cannot withstand such thermal shocks, leading to substrate damage or device failure.

[0004] Furthermore, due to the chemical inertness of PFA molecular chains and the highly fluorinated surface characteristics, its surface energy is extremely low, resulting in very weak natural adhesion between it and common substrates such as silicon, metals, and glass. PFA films prepared by traditional physical coating methods (such as hot melt coating or solution casting followed by high-temperature baking) often suffer from delamination, peeling, or even complete detachment due to insufficient interfacial bonding, failing to meet the long-term stability and reliability requirements of precision devices.

[0005] Therefore, developing a technical solution that can be processed under mild low-temperature conditions and significantly improve the interfacial adhesion between the PFA film and the substrate is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] Existing methods for preparing PFA films for chips typically employ high-temperature heat treatment processes. This process is not only energy-intensive, but the high temperatures can also damage the increasingly delicate and heat-sensitive structures within the chip. Furthermore, the chemical inertness of PFA itself results in insufficient physical adhesion to the chip substrate (such as silicon dioxide or silicon nitride), making it prone to delamination failure in subsequent processes or long-term use. Physical fillers added to improve performance suffer from uneven dispersion and agglomeration, affecting the uniformity and stability of the film's performance.

[0007] Therefore, the present invention aims to provide a method for preparing a high-performance PFA film for chips, in order to solve the technical problems of high process temperature, weak adhesion between film and substrate, and poor performance uniformity in the prior art.

[0008] To address the aforementioned technical problems, this invention provides a method for preparing a high-performance PFA film for chips. This method first requires the preparation of a photosensitive PFA hybrid composition, and then curing it onto a chip substrate as a film through a series of low-temperature process steps.

[0009] Specifically, the photosensitive PFA hybrid composition comprises a solvent and a solid component dissolved therein. Based on the total mass of the solid component, it comprises the following components: 80.0% to 95.0% PFA resin; A multifunctional fluorinated organosilane crosslinking agent comprising 5.0% to 19.5%; A photoinitiator of 0.5% to 2.0%.

[0010] In this solution, the multifunctional fluorinated organosilane crosslinking agent is a key component for achieving low-temperature curing and high interfacial bonding. It has the general chemical formula R... f The structure is -L-Si(OR)3. In this structure, R f The fluorinated alkyl group is PFA-friendly and its function is to improve the compatibility of the crosslinking agent in a PFA resin-based matrix; L is a photosensitive functional group that can polymerize under ultraviolet light and its function is to form a crosslinked network structure under light irradiation to enhance the mechanical properties of the film; Si(OR)3 is a hydrolyzable silane group and its function is to react with active groups (such as hydroxyl groups) on the surface of the chip substrate to form chemical bonds.

[0011] In one specific implementation, the R f The group is a C4 to C8 perfluoroalkyl group.

[0012] To enable the implementation of the technical solution of the present invention, a method for preparing the multifunctional fluorinated organosilane crosslinking agent will be described in detail below: This preparation method comprises two main steps. The first step is the esterification reaction of a fluorinated alcohol with acryloyl chloride, and the second step is the addition reaction of the esterification product with a silane. The specific steps are as follows: (1) Synthesis of 1H,1H,2H,2H-perfluorooctyl methacrylate: In a three-necked flask equipped with a reflux condenser, a dropping funnel, and a magnetic stirrer, 1H,1H,2H,2H-perfluorooctanoic acid, triethylamine, and anhydrous tetrahydrofuran were added. The mixture was placed in an ice-water bath at 0–5 °C. While stirring, methacryloyl chloride dissolved in anhydrous tetrahydrofuran was slowly added dropwise through the dropping funnel, maintaining the reaction temperature below 10 °C during the addition. After the addition was complete, the reaction mixture was stirred at room temperature for 12 hours. After the reaction was complete, the solid salts were removed by filtration, and the solvent was removed by vacuum distillation of the filtrate. The crude product was washed sequentially with saturated sodium bicarbonate solution and deionized water, and then dried over anhydrous magnesium sulfate. Finally, the product was purified by filtration and vacuum distillation, and the target fraction was collected to obtain 1H,1H,2H,2H-perfluorooctanoic acid as an intermediate.

[0013] (2) Final synthesis of the target crosslinking agent: In a clean, dry three-necked flask equipped with a reflux condenser, a dropping funnel, and a magnetic stirrer, 1H,1H,2H,2H-perfluorooctyl methacrylate prepared in step (1) and anhydrous toluene were added. Nitrogen gas was bubbled through the reaction system for protection, and a castor catalyst was added. The reaction system was heated to 75-85°C, and triethoxysilane was slowly added dropwise through the dropping funnel. After the addition was complete, the reaction mixture was stirred at this temperature for 24 hours, and the reaction endpoint was determined by monitoring the disappearance of a specific infrared absorption peak. After the reaction was complete, the system was cooled to room temperature, and the solvent and excess reactants were removed by vacuum distillation to obtain the multifunctional fluorinated organosilane crosslinking agent as the final product. The product was sealed and stored under nitrogen protection for later use.

[0014] The function of the photoinitiator is to initiate a polymerization reaction of the photosensitive functional groups of the crosslinking agent after absorbing light energy of a specific wavelength.

[0015] In one specific embodiment, a photobleaching initiator is selected. This type of initiator is characterized by the fact that its decomposition products have lower light absorption at the exposure wavelength than their pre-decomposition state. This characteristic increases the penetration depth of ultraviolet light within the film layer, contributing to uniform curing of the thick film. For example, acylphosphine oxide initiators can be used as the photobleaching initiator.

[0016] The preparation method of the present invention includes the following sequential process steps: First, the composition solution is prepared. The PFA resin, multifunctional fluorinated organosilane crosslinking agent, and photoinitiator in the above proportions are dissolved in a suitable solvent to form a homogeneous and stable photosensitive PFA hybrid composition solution.

[0017] Next, the composition solution is coated onto a chip substrate to form a wet film. A specific coating method is spin coating.

[0018] Next, the wet film undergoes a low-temperature pre-baking treatment. This step is carried out in the temperature range of 80°C to 100°C, and its purpose is to remove most of the solvent from the wet film, forming a solid film suitable for subsequent exposure.

[0019] Subsequently, the film is exposed to ultraviolet light. The center wavelength range of the ultraviolet light source can be set to 320nm to 450nm, and the exposure dose range can be set to 50mJ / cm². 2 Up to 500mJ / cm 2 In this step, the photoinitiator absorbs light energy and initiates a crosslinking reaction in the photosensitive functional group L of the crosslinking agent.

[0020] Finally, the exposed film undergoes a low-temperature post-baking treatment. This step is performed within a temperature range of 100°C to 130°C. This step provides energy to promote a more complete crosslinking reaction and drives the Si(OR)3 groups at the ends of the crosslinking agent molecules to undergo a de-alcoholization condensation reaction with the hydroxyl groups on the chip substrate surface, completing the chemical bonding and thus forming the high-performance PFA film on the chip substrate. When the surface of the chip substrate is a silicon dioxide or silicon nitride layer, the chemical bonding specifically manifests as Si-O-substrate covalent bonds formed at the interface between the film layer and the substrate.

[0021] In summary, the present invention has at least one of the following beneficial technical effects: 1. This invention uses ultraviolet light exposure to initiate cross-linking, supplemented by low-temperature pre-baking and post-baking treatments at no higher than 130°C, to form a complete low-temperature curing process. This method completely replaces the high-temperature heat treatment steps that require temperatures above 180°C in the prior art, thereby effectively avoiding potential damage to heat-sensitive components or structures inside the chip caused by high temperatures, and improving process compatibility with advanced packaging and complex chip structures.

[0022] 2. This invention solves the problem of weak adhesion between traditional PFA films and chip substrates by introducing a specially designed multifunctional fluorinated organosilicon crosslinking agent into the composition. The crosslinking agent contains hydrolyzable silane groups in its molecular structure. During the low-temperature post-baking step, these groups undergo a de-alcoholization condensation reaction with the hydroxyl groups on the surface of the chip substrate to form stable Si-O-substrate covalent bonds, achieving chemical anchoring between the film layer and the substrate. Compared with physical adsorption, this significantly improves the bonding strength and long-term reliability of the interface.

[0023] 3. This invention integrates the functions of enhancing the mechanical properties of the film and improving interfacial adhesion into a single multifunctional fluorinated organosilane crosslinking agent molecule, and completes this process in one step through a unified photocuring process. This method integrates the processes of polymerizing the photosensitive functional groups of the crosslinking agent to enhance the cohesive strength of the film and the reaction of its silane groups with the substrate to enhance adhesion into a simplified low-temperature process, which simplifies the production process compared to traditional processes that require multiple steps (such as plasma modification, multilayer coating, etc.). Detailed Implementation

[0024] The present invention will be further described in detail below with reference to Examples 1-3, Comparative Examples 1-2 and Test Examples 1-2.

[0025] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0026] 1H,1H,2H,2H-Perfluorooctanoic acid, CAS:647-42-7; N-Methylpyrrolidone, CAS: 872-50-4; PFA resin, CAS: 60699-51-6; Acetone, CAS: 67-64-1; Photoinitiator TPO, CAS: 75980-60-8; Toluene, CAS: 108-88-3; Methacrylamide chloride, CAS: 79-39-0; Methyl isobutyl ketone, CAS: 108-10-1; Karstedt's catalyst, CAS: 68478-92-2; Triethylamine, CAS: 121-44-8; Triethoxysilane, CAS: 998-30-1; Tetrahydrofuran, CAS: 109-99-9; Sodium bicarbonate, CAS: 144-55-8; Hydrofluoroether, CAS: 406-78-0; Anhydrous magnesium sulfate, CAS: 7487-88-9.

[0027] Preparation Example 1: Preparation of Multifunctional Fluorinated Organosilanes Crosslinking Agents This preparation example aims to illustrate a method for obtaining a multifunctional fluorinated organosilicon crosslinking agent used in embodiments of the present invention.

[0028] (1) Synthesis of 1H,1H,2H,2H-perfluorooctyl methacrylate: In a 500 mL three-necked flask equipped with a reflux condenser, a constant pressure dropping funnel, and a magnetic stirrer, 50.0 g (0.12 mol) of 1H,1H,2H,2H-perfluorooctyl alcohol, 18.2 g (0.18 mol) of triethylamine, and 200 mL of anhydrous tetrahydrofuran were added sequentially. The magnetic stirrer was started, and the three-necked flask was placed in an ice-water bath to cool the internal material temperature to 0-5 °C.

[0029] Methacrylamide chloride (15.1 g, 0.14 mol) was dissolved in 50 mL of anhydrous tetrahydrofuran and transferred to the constant-pressure dropping funnel. The tetrahydrofuran solution of methacrylamide chloride was slowly added dropwise to a three-necked flask under vigorous stirring over approximately 1 hour, with the dropping rate controlled to maintain the internal temperature of the reaction system below 10 °C.

[0030] After the dropwise addition was completed, the ice-water bath was removed, and the reaction system was continuously stirred at room temperature (approximately 25°C) for 12 hours. After the reaction was completed, the mixture was filtered using a Buchner funnel to remove the white solid precipitate (triethylamine hydrochloride) formed during the reaction. The collected filtrate was transferred to a rotary evaporator, and the solvent tetrahydrofuran was evaporated under reduced pressure to obtain a yellow oily crude product.

[0031] The crude product was washed with a saturated sodium bicarbonate aqueous solution three times; then washed with deionized water until neutral. The washed organic phase was dried with anhydrous magnesium sulfate, and then filtered to remove the desiccant. Finally, the filtrate was distilled under reduced pressure, and the fraction at a specific boiling point was collected to obtain a colorless, transparent liquid product, namely 1H,1H,2H,2H-perfluorooctyl methacrylate, which was sealed for later use.

[0032] (2) The final synthesis of the target crosslinking agent was carried out in a 250 mL clean three-necked flask that had been thoroughly dried and equipped with a reflux condenser, a constant pressure dropping funnel and a magnetic stirrer. The 1H,1H,2H,2H-perfluorooctyl methacrylate (23.5 g, 0.05 mol) and 100 mL of anhydrous toluene obtained in step (1) were added.

[0033] Nitrogen gas was continuously introduced into the reaction system to provide an inert atmosphere, and a Karstedt's catalyst solution (0.1 mL of xylene solution with a platinum content of 2%) was added.

[0034] The reaction system was heated to a temperature range of 75-85°C, and triethoxysilane (9.0 g, 0.055 mol) was slowly added dropwise through a constant-pressure dropping funnel. The addition process was completed within 30 minutes. After the addition was complete, the reaction mixture was stirred continuously at this temperature for 24 hours. The reaction progress could be monitored using Fourier transform infrared spectroscopy, with the characteristic peak of Si-H stretching vibration (located at approximately 2160 cm⁻¹) as the indicator. -1 The complete disappearance of the reaction site is used as the criterion for determining the endpoint of the reaction.

[0035] After confirming the reaction was complete, the system was cooled to room temperature. The solvent toluene and excess triethoxysilane with a low boiling point were then removed sequentially by vacuum distillation. The final residue was the target product, a multifunctional fluorinated organosilane crosslinking agent. This product was sealed and stored under nitrogen protection for use in subsequent examples.

[0036] Examples 1-3: The multifunctional fluorinated organosilicon crosslinking agents used in the examples were all products obtained in Preparation Example 1. The photoinitiator used was an acylphosphine oxide initiator (TPO).

[0037] Example 1: This embodiment describes the process of preparing a high-performance PFA membrane using a combination of lower limit parameters.

[0038] (1) Preparation of the composition solution: Accurately weigh 95.0% of the PFA resin, 5.0% of the multifunctional fluorinated organosilane crosslinking agent prepared in Preparation Example 1, and 0.5% of the photoinitiator (TPO) based on the total mass percentage of the solid components. Add the above three solid components to a hydrofluoroether (HFE) solvent and stir at room temperature until all solid components are completely dissolved, forming a clear, homogeneous solution. Adjust the amount of hydrofluoroether (solvent) so that the total mass fraction of the solid components in the final prepared photosensitive PFA hybrid composition solution is 10%.

[0039] (2) Preparation of PFA membrane: Place a clean silicon wafer on the turntable of a spin coater. Take an appropriate amount of the prepared composition solution from step (1) and drop it onto the center of the silicon wafer. Start the spin coater and spin-coat the solution evenly onto the substrate surface to form a wet film.

[0040] Subsequently, the silicon wafer substrate coated with the wet film is transferred to a hot plate and subjected to a low-temperature pre-baking treatment at 80°C for 180 seconds to remove the solvent and form an adhesive film.

[0041] The substrate with the adhesive film was placed under a UV exposure machine and exposed using a UV light source with a center wavelength of 320nm, with the exposure dose controlled at 50mJ / cm². 2 .

[0042] After exposure, the substrate is placed back on a hot plate and subjected to a low-temperature post-baking process at 100°C for 600 seconds. After the post-baking is complete, it is allowed to cool naturally to room temperature, resulting in a high-performance PFA film on the silicon wafer substrate.

[0043] Example 2: This embodiment describes the process of preparing a high-performance PFA membrane using a combination of parameters within the middle limit.

[0044] (1) Preparation of the composition solution: Accurately weigh 87.0% of PFA resin, 12.0% of the multifunctional fluorinated organosilane crosslinking agent prepared in Preparation Example 1, and 1.0% of the photoinitiator (TPO) according to the total mass percentage of the solid components. Add the above three solid components to a mixed solvent of hydrofluoroether (solvent) and methyl isobutyl ketone (volume ratio 1:1), and stir at room temperature until all solid components are completely dissolved. Adjust the amount of mixed solvent so that the total mass fraction of solid components in the final prepared photosensitive PFA hybrid composition solution is 18%.

[0045] (2) The PFA film was prepared by spin coating in the same way as in Example 1. The composition solution prepared in step (1) was coated onto a clean silicon substrate to form a wet film.

[0046] The silicon wafer substrate coated with a wet film is transferred to a hot plate and subjected to a low-temperature pre-baking treatment at 90°C for 120 seconds.

[0047] The substrate with the adhesive film was placed under a UV exposure machine and exposed using a UV light source with a center wavelength of 365nm, with the exposure dose controlled at 250mJ / cm². 2 .

[0048] After exposure, the substrate is placed back on a hot plate and subjected to a low-temperature post-baking treatment at 115°C for 300 seconds. After the post-baking is complete, it is allowed to cool naturally to room temperature to obtain a high-performance PFA film.

[0049] Example 3: This embodiment describes the process of preparing a high-performance PFA membrane using a combination of upper limit parameters.

[0050] (1) Preparation of the composition solution: Accurately weigh 80.0% of PFA resin, 18.0% of the multifunctional fluorinated organosilane crosslinking agent prepared in Preparation Example 1, and 2.0% of the photoinitiator (TPO) according to the total mass percentage of the solid components. Add the above three solid components to the hydrofluoroether solvent and stir at room temperature until all solid components are completely dissolved. Adjust the amount of solvent so that the total mass fraction of solid components in the final prepared photosensitive PFA hybrid composition solution is 25%.

[0051] (2) The PFA film was prepared by spin coating in the same way as in Example 1. The composition solution prepared in step (1) was coated onto a clean silicon substrate to form a wet film.

[0052] The silicon wafer substrate coated with a wet film is transferred to a hot plate and subjected to a low-temperature pre-baking treatment at 100°C for 60 seconds.

[0053] The substrate with the adhesive film was placed under a UV exposure machine and exposed using a UV light source with a center wavelength of 450nm, with the exposure dose controlled at 500mJ / cm². 2 .

[0054] After exposure, the substrate is placed back on a hot plate and subjected to a low-temperature post-baking treatment at 130°C for 180 seconds. After the post-baking is complete, it is allowed to cool naturally to room temperature to obtain a high-performance PFA film.

[0055] Comparative Examples 1-2: Comparative Example 1: Compared with Example 2, the difference is that this comparative example uses a traditional high-temperature thermosetting method. Its composition contains only PFA resin, without the addition of multifunctional fluorinated organosilicon crosslinking agents and photoinitiators; its preparation process involves directly baking the film at 220°C after spin coating, without low-temperature pre-baking, UV exposure, or low-temperature post-baking treatments.

[0056] Comparative Example 2: Compared to Example 2, the difference lies in that the solid component of the composition does not contain a multifunctional fluorinated organosilane crosslinking agent (correspondingly, the content of PFA resin is adjusted to 99.0%, and the content of photoinitiator is adjusted to 1.0%). All other preparation steps, including the solvents used, spin coating process, low-temperature pre-baking, UV exposure, and low-temperature post-baking process parameters, are exactly the same as in Example 2.

[0057] Test Example 1-2: Test Example 1: Adhesion Test This test example aims to evaluate the adhesion strength between the films prepared in each embodiment and the silicon substrate. The test method was performed in accordance with ASTM D3359-17 (cross-cut test).

[0058] The specific experimental steps are as follows: Place the sample to be tested (a silicon wafer with a pre-prepared PFA film) on a stable, level testing platform.

[0059] A multi-blade cutter with 11 blades spaced 1 mm apart is selected. Hold the cutter roughly perpendicular to the surface of the film to be tested, apply uniform and sufficient pressure, and make 11 parallel cuts on the film with a smooth and uninterrupted motion, ensuring that each cut penetrates the film and reaches the substrate.

[0060] Rotate the cutter 90 degrees and repeat step 2 on the existing cut to form a grid area consisting of 100 (10x10) 1mm×1mm small squares.

[0061] Use a soft brush to gently sweep along the grid area diagonally to remove debris from the surface cutting.

[0062] Take a piece of pressure-sensitive tape that meets the standard requirements (such as 3MScotch 610 tape) and cover the entire grid area. Rub the tape back and forth vigorously with your finger or an eraser to ensure full, bubble-free contact between the tape and the film layer.

[0063] After applying the tape for 30 to 60 seconds, hold the free end of the tape and gently peel it off the film surface at an angle as close to 180 degrees as possible within 0.5 to 1 second.

[0064] Under sufficient light, the film peeling in the grid area was observed using a magnifying glass, and the adhesion was rated according to the percentage of peeling area specified in ASTM D3359-17. The rating ranged from 5B (completely smooth cut edges with no square peeling) to 0B (film peeling area greater than 65%). Each sample was tested three times, and the worst rating was taken as the final result.

[0065] Performance test results and analysis: The PFA membranes prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests according to the method in Test Example 1, and the results are summarized in Table 1 below.

[0066] Table 1. Adhesion test results for each sample Test sample Adhesion rating (ASTM D3359) Example 1 4B Example 2 5B Example 3 5B Comparative Example 1 1B Comparative Example 2 0B In summary, the test results in Table 1 show that the films prepared by the method of this invention in Examples 1, 2, and 3 all achieved an adhesion grade of 4B or 5B, indicating a very strong bond between the film and the substrate. In contrast, Comparative Example 1, which used a conventional high-temperature film-forming method, had an adhesion grade of only 1B, exhibiting significant peeling. Comparative Example 2, lacking the key crosslinking agent component, experienced severe peeling over a large area, with an adhesion grade of 0B.

[0067] The fundamental reason for the differences in the above test results lies in the different interfacial interaction mechanisms between the film layer and the substrate. In the technical solutions of Examples 1, 2, and 3, the multifunctional fluorinated organosilane crosslinking agent introduced has a hydrolyzable triethoxysilane group at one end of its molecular structure. During the low-temperature post-baking process, this group undergoes a hydrolytic condensation reaction on the substrate surface, forming a chemical bond with the hydroxyl groups on the substrate surface, i.e., generating a stable Si-O-substrate covalent bond at the interface. The force of this chemical bonding is much greater than the physical van der Waals force, thus providing a solid chemical anchor for the film layer, resulting in its extremely high adhesion strength. The formulations of Comparative Examples 1 and 2 do not contain this crosslinking agent, and there is only weak physical adsorption between the film layer and the substrate. Therefore, under the external forces of cross-cutting and tape tearing, interfacial separation easily occurs.

[0068] Furthermore, the completeness of the technical solution of this invention is reflected in its synergistic effect. During the ultraviolet light exposure step, the photosensitive functional groups in the multifunctional fluorinated organosilicon crosslinking agent molecules undergo polymerization, forming a crosslinked network structure in the PFA matrix, thereby enhancing the cohesive strength and mechanical integrity of the film layer itself. Therefore, it is through this series of process steps—low-temperature pre-baking, ultraviolet exposure, and low-temperature post-baking—that the crosslinking polymerization of the crosslinking agent within the film layer and its chemical bonding at the film-substrate interface are synergistically driven, ultimately resulting in a high-performance PFA film with both high cohesive strength and high interfacial adhesion under low-temperature conditions.

[0069] Test Example 2: Solvent Resistance Test This test example aims to evaluate the degree of crosslinking and curing of the films prepared in each embodiment and comparative example. The test characterizes the films by evaluating their resistance to abrasion in specific solvents.

[0070] The specific experimental steps are as follows: The sample to be tested (a silicon wafer with a pre-prepared PFA film) is fixed on a horizontal test platform.

[0071] Wrap a standard piece of cotton cloth around a friction head with a 1kg load.

[0072] Use a dropper to apply acetone to a cotton cloth until it is completely soaked.

[0073] Place the friction head with the wetted cotton cloth on the surface of the film to be tested, and start the reciprocating friction tester.

[0074] The friction head is set to reciprocate linearly at a frequency of 40 times / minute over a stroke length of 30mm. One reciprocation is counted as one friction cycle.

[0075] After every 50 rubbing cycles, pause the test and visually inspect the film surface for scratches, damage, or exposure of the substrate. If no damage is found, continue the test.

[0076] Record the total number of rubbing cycles until the first permanent scratch appears on the film surface or the substrate is exposed. If the film layer shows no obvious damage after more than 300 rubbing cycles, stop the test and record it as ">300".

[0077] Performance test results and analysis: The PFA membranes prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests according to the method in Test Example 2, and the results are summarized in Table 2 below.

[0078] Table 2. Solvent resistance test results for each sample Test sample Solvent resistance (number of acetone rubs) Example 1 172 Example 2 >300 Example 3 >300 Comparative Example 1 6 Comparative Example 2 9 In summary, the test results in Table 2 show that the films prepared by the method of this invention in Examples 1, 2, and 3 all exhibit high resistance to acetone solvent, with each film undergoing more than 170 rub cycles. In contrast, the films in Comparative Examples 1 and 2 were destroyed after only a very low number of rub cycles. This result indicates that the films prepared in these examples form a stable chemical structure different from that of the comparative film layers.

[0079] The aforementioned differences in solvent resistance stem from the formation of the internal network structure of the film. In the technical solutions of Examples 1, 2, and 3, the composition includes a photoinitiator and a multifunctional fluorinated organosilane crosslinking agent. During the ultraviolet light exposure process, the photoinitiator decomposes after absorbing photon energy of a specific wavelength, generating highly reactive free radicals. These free radicals then initiate a chain polymerization reaction of the photosensitive functional groups (methacrylate groups) on the crosslinking agent molecules. This reaction forms stable carbon-carbon covalent bonds between different crosslinking agent molecules, thereby constructing a three-dimensional crosslinked network structure in the PFA resin matrix. This network structure restricts the movement of polymer chain segments and effectively hinders the penetration and swelling of small molecule solvents such as acetone into the film, thus macroscopically exhibiting high solvent friction resistance.

[0080] Comparative Example 1 consists only of PFA resin, a linear thermoplastic polymer. The molecular chains interact only through van der Waals forces and physical entanglement, without covalent cross-linking. Therefore, solvent molecules can easily penetrate, swell, and destroy the film structure, resulting in extremely low solvent resistance. Although Comparative Example 2 includes a photoinitiator and has undergone exposure treatment, it lacks a cross-linking agent component containing polymerizable functional groups, preventing the formation of a cross-linked network during exposure. Its essence remains a thermoplastic PFA film, hence its solvent resistance is similarly low to Comparative Example 1. This comparison confirms that the introduction of a specific cross-linking agent, combined with photoinitiation and post-baking processes, ultimately leads to the formation of a chemical cross-linked network, which is the direct reason for the high solvent resistance of the films in these examples.

[0081] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high-performance PFA film for chips, characterized in that, Includes the following steps: A photosensitive PFA hybrid composition solution is prepared, wherein the composition comprises a solvent and a solid component dissolved in the solvent, and the solid component comprises, by weight of the total solid component: 80.0% to 95.0% PFA resin; 5.0% to 19.5% of multifunctional fluorinated organosilane crosslinking agents; 0.5% to 2.0% photoinitiator; The composition solution is coated onto a chip substrate to form a wet film; The wet film is pre-baked at low temperature to remove the solvent and form an adhesive film; The film is exposed to ultraviolet light to initiate a crosslinking reaction in the crosslinking agent; The exposed adhesive film is then subjected to low-temperature post-baking to complete cross-linking and chemical bonding, thereby forming the high-performance PFA film on the chip substrate.

2. The method for preparing a high-performance PFA film for chips according to claim 1, characterized in that, The multifunctional fluorinated organosilane crosslinking agent has the general chemical formula R. f -L-Si(OR)3, where R f L is a fluorinated alkyl group that is PFA-friendly; L is a photosensitive functional group that can polymerize under ultraviolet light initiation; Si(OR)3 is a hydrolyzable silane group that can react with the surface of the chip substrate to form chemical bonds.

3. The method for preparing a high-performance PFA film for chips according to claim 1, characterized in that, R in the crosslinking agent f The group is a C4 to C8 perfluoroalkyl group.

4. The method for preparing a high-performance PFA film for chips according to claim 1, characterized in that, The photoinitiator is a photobleaching type initiator.

5. The method for preparing a high-performance PFA film for chips according to claim 4, characterized in that, The photobleaching initiator is an acylphosphine oxide initiator.

6. The method for preparing a high-performance PFA film for chips according to claim 1, characterized in that, The temperature range for the low-temperature pre-baking is 80°C to 100°C.

7. The method for preparing a high-performance PFA film for chips according to claim 1, characterized in that, The temperature range for the low-temperature post-drying is 100°C to 130°C.

8. The method for preparing a high-performance PFA film for chips according to claim 1, characterized in that, The ultraviolet light has a center wavelength of 320 nm to 450 nm and an exposure dose range of 50 mJ / cm². 2 Up to 500mJ / cm 2 .

9. The method for preparing a high-performance PFA film for chips according to claim 1, characterized in that, The coating method is spin coating.

10. The method for preparing a high-performance PFA film for chips according to claim 1, characterized in that, The surface of the chip substrate is a silicon dioxide or silicon nitride layer, and the chemical bonding is a Si-O-substrate covalent bond formed between the hydrolyzable silane group of the multifunctional fluorinated organosilicon crosslinking agent and the hydroxyl group on the substrate surface.