An LCP thin-film module, its preparation method and application

Abstract

This application provides an LCP thin film assembly, its preparation method, and its application. The preparation method includes: surface modification of the LCP thin film to obtain an activated surface rich in carboxyl and hydroxyl groups, followed by hot pressing of the LCP thin film with the activated surface; the LCP thin film assembly includes a multilayer LCP thin film bonded by hot pressing, wherein no adhesive is contained between any two adjacent LCP thin films, and the interface region between any two adjacent LCP thin films forms a homogenized molecular-level bonding layer through melt recrystallization; the preparation method of this application introduces active functional groups through surface modification methods such as alkaline hydrolysis and acid activation, achieving interlayer chemical bonding during hot pressing, significantly improving interlayer bonding strength, avoiding the risks of bubbling and delamination, and retaining the inherent excellent high-frequency performance and dielectric properties of the LCP thin film; this preparation method, when applied to the preparation of LCP thin film probe cards, can produce thin film probe cards with excellent interlayer bonding strength and high-frequency performance.

Description

Technical Field

[0001] This application relates to the fields of microelectronic packaging and high-frequency communication technology, and in particular to an LCP thin film component, its preparation method and application. Background Technology

[0002] With the rapid development of fifth-generation mobile communication technology (5G) and higher-frequency millimeter-wave technology, high-end electronic components such as thin-film probe cards in the semiconductor testing field are placing unprecedented demands on the performance of core materials. These materials must possess extremely low signal loss at high frequencies, stable impedance characteristics, excellent dimensional stability, and resistance to complex stresses. Traditional insulating materials, such as polyimide or epoxy resin substrates, are no longer sufficient to meet the application requirements of high-frequency and high-speed scenarios due to their high dielectric loss and hygroscopicity.

[0003] Liquid crystal polymer (LCP) films have advantages such as low dielectric loss, low dielectric constant, high heat resistance, and excellent dimensional stability. They are widely regarded as ideal materials for manufacturing interlayer insulation and circuit boards in components such as thin-film probe cards and flexible antennas used in high-frequency applications.

[0004] From LCP thin films to final electronic devices, the core challenge lies in achieving effective bonding of multilayer LCP thin films. Currently, the mainstream processes include direct hot pressing and adhesive bonding. Direct hot pressing involves heating and pressurizing the LCP film interfaces to melt, diffuse, and fuse. However, due to the poor fluidity, smooth surface, and low surface energy of LCP films, the polymer chains between layers cannot fully diffuse and entangle. Therefore, multilayer LCP thin film components obtained by direct hot pressing are prone to incomplete bonding problems such as bubbling, leading to delamination and failure during processing or use. Adhesive bonding uses an intermediate adhesive layer for bonding; however, the introduced organic adhesive can increase dielectric constant and dielectric loss, and reduce heat resistance, sacrificing the inherent excellent high-frequency performance of LCP materials. Summary of the Invention

[0005] The purpose of this application is to overcome the shortcomings of the prior art and provide an LCP thin film module, its preparation method and application, which do not change the dielectric properties and stability of the LCP thin film and improve the interlayer bonding of the LCP thin film.

[0006] To achieve the above objectives, the first aspect of this application provides a method for preparing an LCP thin film module, comprising: surface modification of an LCP thin film to obtain an activated surface rich in carboxyl and hydroxyl groups, and hot-pressing the LCP thin film with the activated surface to cause a bonding reaction between the active functional groups of adjacent LCP thin films at the interface; the surface modification includes the following steps: S1, plasma treatment of the LCP thin film to obtain a treated LCP thin film; S2, immersing the surface of the treated LCP thin film in an organic solvent for swelling treatment; S3, immersing the swollen surface of the LCP thin film in an alkaline solution for alkaline hydrolysis treatment; S4, cleaning the LCP thin film and immersing its alkaline hydrolyzed surface in dilute hydrochloric acid to obtain an activated surface rich in carboxyl and hydroxyl groups.

[0007] In one feasible embodiment, in step S1, the power of the plasma treatment is 200-400W, and the duration of the plasma treatment is 200-400s.

[0008] In a feasible embodiment, in step S2, the organic solvent is one or more of methanol, ethanol, acetone, ethyl acetate, p-xylene, chloroform, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone.

[0009] In one feasible embodiment, the swelling treatment temperature is 50-80°C, and the swelling treatment time is 1-5 minutes.

[0010] In a feasible embodiment, in step S3, the alkaline solution is an inorganic alkaline solution, an organic alkaline solution, or a mixed solution of inorganic and organic alkalines.

[0011] In one feasible embodiment, the mass concentration of the alkaline solution is 5-95 wt%, the temperature of the alkaline hydrolysis treatment is 50-80°C, and the immersion time is 1-5 min.

[0012] In one feasible embodiment, the inorganic base is one or more of sodium hydroxide and potassium hydroxide.

[0013] In one feasible embodiment, the organic base is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

[0014] In one feasible embodiment, in step S4, the mass concentration of the dilute hydrochloric acid is 10-15 wt%, and the dilute hydrochloric acid immersion treatment time is 1-5 min.

[0015] In one feasible embodiment, the method includes the following steps: Step 1, providing a surface-modified bottom LCP film, wherein a circuit layer is deposited on the upper surface of the bottom LCP film; Step 2, providing a surface-modified intermediate LCP film, which is stacked on the bottom LCP film, and hot-pressing the stacked bottom LCP film and intermediate LCP film under heating and pressure conditions; Step 3, electroplating a circuit layer on the upper surface of the hot-pressed intermediate LCP film; Step 4, stacking a surface-modified top LCP film on the upper surface of the intermediate LCP film with the circuit layer, and hot-pressing the stacked bottom LCP film, intermediate LCP film, and top LCP film under heating and pressure conditions to obtain an LCP film assembly.

[0016] In one feasible embodiment, the hot pressing is performed under vacuum conditions, and the hot pressing temperature is 150-300°C, the pressing pressure is 200-400 psi, and the hot pressing time is 30-90 min.

[0017] In one feasible embodiment, the surface-modified LCP film is cleaned and dried before hot pressing, with a drying temperature of 80-200°C and a drying time of 10-30 min.

[0018] A second aspect of this application provides an LCP thin film assembly obtained by the above preparation method, comprising a multilayer LCP thin film bonded by hot pressing, wherein no adhesive is contained between any two adjacent LCP thin films, and the interface region between any two adjacent LCP thin films forms a homogenized molecular-level bonded layer through melt recrystallization and functional group bonding.

[0019] The third aspect of this application provides the application of the preparation method described above in the preparation of LCP thin film probe cards.

[0020] This application has the following advantages compared with the prior art:

[0021] This application introduces active functional groups into the LCP film surface through surface modification methods such as alkaline hydrolysis and acid activation. During hot pressing, interlayer chemical bonding is achieved, causing the active functional groups at the interface of the two LCP films to condense and form covalent bonds. The polymer chains diffuse and entangle to form a homogenized molecular-level bonded layer, whose physical properties (such as dielectric constant and coefficient of thermal expansion) are consistent with the core material, achieving a seamless transition. This application significantly improves the interlayer adhesion of LCP films without the need for interlayer adhesives, avoiding the risks of bubbling and delamination, while retaining the inherent excellent high-frequency and dielectric properties of LCP films. Attached Figure Description

[0022] Figure 1This is a schematic diagram illustrating the hot pressing preparation of two surface-modified LCP films in an embodiment of this application.

[0023] Figure 2 This is a SEM image of the cross-section of the hot-pressed interface of the surface-modified LCP film in the embodiments of this application. Specific Implementation

[0024] To illustrate the technical content, structural features, achieved objectives, and effects of the invention in detail, the technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. In the following description, for illustrative purposes, numerous specific details are set forth to provide a detailed description of various exemplary embodiments or implementations of the invention. However, various exemplary embodiments may also be implemented independently without these specific details or in one or more equivalent arrangements. Furthermore, the various exemplary embodiments may differ, but are not necessarily exclusive. For example, the specific shape, construction, and characteristics of the exemplary embodiments may be used or implemented in another exemplary embodiment without departing from the inventive concept.

[0025] This application provides a method for preparing an LCP thin film module, comprising: modifying the surface of an LCP thin film to obtain an activated surface rich in carboxyl and hydroxyl groups, and then hot-pressing the LCP thin film with the activated surface to form a composite, thereby causing the active functional groups of two adjacent LCP thin films to undergo a bonding reaction, thereby increasing the bonding force between the layers.

[0026] Surface modification includes the following steps:

[0027] S1, The LCP film is subjected to plasma treatment to obtain the treated LCP film;

[0028] S2, the surface of the treated LCP film is immersed in an organic solvent for swelling treatment;

[0029] S3, the surface of the swollen LCP film is immersed in an alkaline solution for alkaline hydrolysis treatment;

[0030] S4. The LCP film is cleaned and its alkaline hydrolyzed surface is impregnated with dilute hydrochloric acid to obtain a modified and activated surface rich in carboxyl and hydroxyl groups. This surface modification introduces active functional groups into the LCP film surface through a combination of physical and chemical processes, thereby providing a foundation for subsequent high-bonding hot pressing without introducing additional adhesives, while retaining the inherent excellent high-frequency performance of the LCP film.

[0031] Furthermore, the preparation method of LCP thin-film modules specifically includes the following steps:

[0032] Step 1: Provide a surface-modified base LCP film, with a circuit layer deposited on the upper surface of the base LCP film;

[0033] Step 2: Provide a surface-modified intermediate LCP film and stack it on the bottom LCP film. Then, heat-press the stacked bottom LCP film and intermediate LCP film under heating and pressure conditions to form a composite.

[0034] Step 3: Electroplating a circuit layer on the upper surface of the intermediate LCP film after hot pressing and bonding;

[0035] Step 4: A surface-modified surface LCP film is laminated on the upper surface of the intermediate LCP film with the circuit layer. The laminated bottom LCP film, intermediate LCP film and surface LCP film are hot-pressed under heating and pressure to obtain an LCP film assembly.

[0036] The upper surface of the bottom LCP film with the circuit layer, the lower surface of the middle LCP film, the upper surface of the LCP film with the circuit layer, and the lower surface of the top LCP film are all modified by the aforementioned surface modification method.

[0037] During surface modification treatment, in step S1, the plasma treatment power is 200-400W, and the plasma treatment time is 200-400s. The plasma treatment bombards the LCP film surface, removes surface contaminants, and introduces polar groups, thereby improving the surface energy, hydrophilicity, and adhesion of the treated LCP film, creating favorable conditions for subsequent chemical treatment.

[0038] In step S2, the organic solvent is one or more selected from methanol, ethanol, acetone, ethyl acetate, p-xylene, chloroform, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone. Organic solvents have a good swelling effect on LCP, allowing partial swelling of the molecular chain segments on the LCP film surface. This facilitates more uniform penetration and reaction of the subsequent alkaline solution, improving the uniformity and hydrolysis efficiency of the subsequent alkaline hydrolysis treatment. Specifically, the LCP film is immersed in an organic solvent at a temperature of 50-80℃ for 1-5 minutes for swelling treatment. Appropriate temperature and time ensure sufficient swelling of the LCP film surface area while avoiding excessive swelling that could decrease the stability of the LCP film.

[0039] In step S3, the swollen surface of the LCP film is immersed in an alkaline solution with a mass concentration of 5-95 wt% for 1-5 minutes at a temperature of 50-80°C. The alkaline solution can be an inorganic alkaline solution, an organic alkaline solution, or a mixture of inorganic and organic alkalines. Using an alkaline solution allows for adjustment of the hydrolysis rate and effect to meet different process requirements. In this embodiment, the inorganic alkaline is one or more of sodium hydroxide and potassium hydroxide; strong alkalis can effectively catalyze the hydrolysis reaction of ester groups. The organic alkaline is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide; the hydrolysis effect of organic alkalines is relatively mild and helps wet and penetrate the LCP film surface. As an aromatic thermoplastic polyester, one of the main functional groups of the LCP film is the ester group. The alkaline solution causes the ester group portion in the polymer chain on the LCP film surface to hydrolyze to form carboxyl salts and hydroxyl groups, introducing active functional groups and improving the thermal mobility of the surface chain segments of the LCP film during hot pressing.

[0040] In step S4, the mass concentration of dilute hydrochloric acid is 10-15 wt%, and the surface of the LCP film needs to be immersed in dilute hydrochloric acid for 1-5 minutes to activate the carboxyl salt into carboxyl groups, thereby obtaining an active surface with high surface energy.

[0041] like Figure 1 As shown, this application initially improves the surface energy and hydrophilicity of LCP surfaces through plasma treatment; subsequently, it loosens the molecular chain segments of the LCP surface through swelling with organic solvents; then, it partially hydrolyzes the ester groups (-COO-) on the LCP surface using an alkaline solution, converting them into carboxyl salts (-COONa, etc.) and hydroxyl groups (-OH); finally, it is activated with dilute hydrochloric acid to convert the carboxyl salts (-COONa, etc.) into highly reactive carboxyl groups (-COOH), ultimately obtaining an activated surface rich in carboxyl groups (-COOH) and hydroxyl groups (-OH). During subsequent hot pressing, the hydroxyl groups (-OH) and carboxyl groups (-COOH) on this modified surface can undergo a condensation reaction to reform ester groups (-COO-), thereby establishing chemical bonds between LCP layers and significantly improving interlayer bonding. Since no organic adhesives or heterogeneous materials are introduced throughout the modification process, the final product's chemical composition remains pure LCP, thus fully preserving its inherent low dielectric constant and low dielectric loss, and other high-frequency properties.

[0042] In this application, hot pressing is performed under vacuum conditions. The hot pressing temperature is 150-300℃, the pressing pressure is 200-400psi, and the hot pressing time is 30-90min. Hot pressing under vacuum conditions avoids bubble formation and ensures pressing quality. Before hot pressing, the surface-modified LCP film is cleaned and dried at 80-200℃ for 10-30min.

[0043] During this hot-pressing process, the LCP film interface melts and fuses, while surface carboxyl and hydroxyl groups condense to form ester groups, which then interact with the metal of the circuit layer on the LCP film through hydrogen bonding. This enhances the interlayer bonding force of the multilayer LCP film through physical and chemical interactions, constructing a thin-film module with strong interlayer bonding. In this application, the surface modification time is relatively short, with minimal impact on the circuit layer, and does not affect the performance of the LCP thin-film module.

[0044] like Figure 2 As shown, the LCP thin film module obtained by the above preparation method includes a multilayer LCP thin film bonded by hot pressing. No adhesive is contained between any two adjacent LCP thin film layers, and the interface region between any two adjacent LCP thin film layers forms a homogenized molecular-level bonded layer through melt recrystallization. In this region, the original physical interface disappears, and covalent bonds formed by the condensation of active functional groups connect the layers. The mutual diffusion and entanglement of polymer chains form a tight molecular-level bonded layer. This layer structure is dense and free of voids and defects, ensuring that the physical properties of the interface region are consistent with the LCP thin film core material, resulting in overall consistency in macroscopic mechanical and dielectric properties. The LCP thin film module of this application has an adhesive-free integrated structure, with tight bonding between film layers, making it less prone to bubbling and delamination.

[0045] The technical solution provided in this application will be further illustrated below through a comparative example and several embodiments.

[0046] Comparative Example 1:

[0047] LCP film modules were obtained by vacuum hot pressing of multilayer LCP films coated with circuit layers at a temperature of 200℃ and a pressure of 200psi. Testing of the LCP film modules revealed a small amount of blistering between the layers, indicating incomplete interlayer bonding. The dielectric constant was 2.8, the dielectric loss was 0.0020, and the interlayer peel strength was 1.0 kg / cm.

[0048] Example 1:

[0049] First, a circuit layer is electroplated on the upper surface of the bottom LCP film, and the surface modification method is used to modify the upper surface of the bottom LCP film with the circuit layer. Then, the surface modification method is used to modify the lower surface of the intermediate LCP film, and the intermediate LCP film is then laminated onto the bottom LCP film. The laminated bottom LCP film and intermediate LCP film are then hot-pressed under heat and pressure. Next, a circuit layer is electroplated on the upper surface of the intermediate LCP film, and the surface modification method is used to modify the upper surface of the intermediate LCP film with the circuit layer. Finally, the surface modification method is used to modify the lower surface of the top LCP film, and the top LCP film is then laminated onto the intermediate LCP film. The laminated bottom LCP film, intermediate LCP film, and top LCP film are then hot-pressed under heat and pressure to obtain an LCP film assembly.

[0050] The surface modification method of the LCP film in this application embodiment is as follows: the surface of the LCP film to be pressed is bombarded with 300W plasma for 200s; then the surface of the LCP film to be pressed is immersed in dimethylformamide at 70°C for 1min to partially swell the surface of the LCP film; the surface of the LCP film is immersed in sodium hydroxide solution at 60°C and 40wt% for 2min; after cleaning, the surface of the LCP film is immersed in dilute hydrochloric acid at 10wt% for 2min to obtain an activated surface with carboxyl and hydroxyl functional groups.

[0051] In the embodiments of this application, each LCP film layer was thoroughly cleaned after surface modification and dried at 150°C for 20 min. The hot-pressing temperature was 280°C, the pressing pressure was 220 psi, and the hot-pressing time was 60 min.

[0052] The LCP thin film module was tested and found that no bubbling occurred between the layers, indicating that complete and effective bonding was achieved. Its dielectric constant was 2.8, dielectric loss was 0.0020, and interlayer peel strength was 1.7 kg / cm, indicating high reliability.

[0053] Example 2:

[0054] In the method for preparing LCP thin film components in this application embodiment, except for the surface modification method of LCP thin film, the other steps and data are the same as in Example 1.

[0055] The surface modification method of the LCP film in this application embodiment is as follows: the surface of the LCP film to be laminated is bombarded with 300W plasma for 200 s; then the surface of the LCP film to be laminated is immersed in dimethylformamide at 70°C for 3 min to partially swell the surface of the LCP film; the surface of the LCP film is treated with sodium hydroxide solution at 60°C and 40wt% for 2 min; after cleaning, the surface of the LCP film is treated with dilute hydrochloric acid at 10wt% for 2 min to obtain an activated surface with carboxyl and hydroxyl functional groups.

[0056] The LCP thin film module was tested and found that no bubbling occurred between the layers, indicating that complete and effective bonding was achieved. Its dielectric constant was 2.8, dielectric loss was 0.0020, and interlayer peel strength was 1.9 kg / cm, indicating high reliability.

[0057] Example 3:

[0058] In the method for preparing LCP thin film components in this application embodiment, except for the surface modification method of LCP thin film, the other steps and data are the same as in Example 1.

[0059] The surface modification method of the LCP film in this application embodiment is as follows: the surface of the LCP film to be laminated is bombarded with 300W plasma for 200s; then the surface of the LCP film to be laminated is immersed in dimethylformamide at 70°C for 1min to partially swell the surface of the LCP film; the surface of the LCP film is treated with tetramethylammonium hydroxide solution at 60°C and 40wt% for 2min; after cleaning, the surface of the LCP film is treated with dilute hydrochloric acid at 10wt% for 2min to obtain an activated surface with carboxyl and hydroxyl functional groups.

[0060] The LCP thin film module was tested and found that no bubbling occurred between the layers, indicating that a complete and effective bond was achieved. Its dielectric constant was 2.8, dielectric loss was 0.0020, and interlayer peel strength was 2.0 kg / cm, indicating high reliability.

[0061] Example 4:

[0062] In the method for preparing LCP thin film components in this application embodiment, except for the surface modification method of LCP thin film, the other steps and data are the same as in Example 1.

[0063] The surface modification method of the LCP film in this application embodiment is as follows: the surface of the LCP film to be laminated is bombarded with 300W plasma for 200s; then the surface of the LCP film to be laminated is immersed in dimethylformamide at 70°C for 1min to partially swell the surface of the LCP film; the surface of the LCP film is treated with an alkaline solution of equal volume mixture of 40wt% sodium hydroxide and 40wt% tetramethylammonium hydroxide at 60°C for 2min; after cleaning, the surface of the LCP film is treated with 10wt% dilute hydrochloric acid for 2min to obtain an activated surface with carboxyl and hydroxyl functional groups.

[0064] The LCP thin film module was tested and found that no bubbling occurred between the layers, indicating that complete and effective bonding was achieved. Its dielectric constant was 2.8, dielectric loss was 0.0020, and interlayer peel strength was 1.95 kg / cm, indicating high reliability.

[0065] The test results of Comparative Example 1 and Examples 1-4 are summarized in the following table:

[0066] project Interlayer conditions Dielectric constant Dielectric loss Interlayer peel strength (kg / cm) Comparative Example 1 A small number of bubbles 2.8 0.0020 1.0 Example 1 No bubbling 2.8 0.0020 1.7 Example 2 No bubbling 2.8 0.0020 1.9 Example 3 No bubbling 2.8 0.0020 2.0 Example 4 No bubbling 2.8 0.0020 1.95

[0067] As shown in the table above, in Examples 1-4 using the technical solution of this application, the LCP thin film modules have tight and defect-free interlayer bonding, and the interlayer peel strength is increased by 70% to 100% compared with Comparative Example 1. At the same time, the dielectric constant and dielectric loss are completely consistent with pure LCP material, proving that this application can significantly improve the interlayer bonding of LCP thin films without introducing other adhesives, and perfectly retain the excellent high-frequency performance of LCP thin films.

[0068] In one embodiment of this application, the above-described preparation method can be used to fabricate an LCP thin-film probe card. The technical solution of this application is further illustrated by comparing the thin-film probe card assembled using Comparative Example 1 with those assembled using Examples 1 and 2, respectively.

[0069] The following application tests were performed on the assembled thin-film probe card:

[0070] High-frequency signal transmission test: After mounting the thin-film probe card on a special PCB board connected with signal cables and calibrating it, the insertion loss and return loss of the signal lines on the thin-film probe card were tested using a vector network analyzer. The results showed that the insertion loss and return loss of the thin-film probe cards prepared in Examples 1 and 2 were consistent with the theoretical values ​​of pure LCP material; while Comparative Example 1 showed higher insertion loss and return loss under high-frequency signal transmission due to the small gaps between layers.

[0071] Actual wafer testing: After mounting the thin-film probe card on a specially designed PCB board connected with signal cables and calibrating it, the probe tip of the thin-film probe card was aligned with the wafer. After alignment, the probe was slowly lowered to contact the chip pads and electrical tests were performed. The results showed that the thin-film probe cards prepared in Examples 1 and 2 had smooth signal transmission and successful testing during the test; while the thin-film probe card prepared in Comparative Example 1 experienced signal interruption or test failure due to thin-film component delamination. The test yield and test stability of the thin-film probe cards prepared in Examples 1 and 2 were superior to those of the thin-film probe card prepared in Comparative Example 1.

[0072] The LCP thin film module of this application and its application in LCP-type thin film probe cards have excellent interlayer bonding strength and high-frequency performance, which can meet the semiconductor testing needs of fields such as 5G communication, millimeter-wave radar, and high-speed data transmission, and have broad industrial application prospects.

[0073] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope. The scope of protection of the present invention is defined by the appended claims, specification, and their equivalents.

Claims

1. A method for preparing an LCP thin-film module, characterized in that, include: The LCP film undergoes surface modification to obtain an activated surface rich in carboxyl and hydroxyl groups. The activated LCP film is then hot-pressed together, causing the active functional groups of adjacent LCP layers to bond at the interface. The surface modification includes the following steps: S1, The LCP film is subjected to plasma treatment to obtain the treated LCP film; S2, the surface of the treated LCP film is immersed in an organic solvent for swelling treatment; S3, the surface of the swollen LCP film is immersed in an alkaline solution for alkaline hydrolysis treatment; S4, clean the LCP film and impregnate its alkaline hydrolyzed surface with dilute hydrochloric acid to obtain an activated surface rich in carboxyl and hydroxyl groups.

2. The preparation method according to claim 1, characterized in that, In step S1, the power of the plasma treatment is 200-400W, and the plasma treatment time is 200-400s.

3. The preparation method according to claim 1, characterized in that, In step S2, the organic solvent is one or more of methanol, ethanol, acetone, ethyl acetate, p-xylene, chloroform, tetrahydrofuran, dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methylpyrrolidone.

4. The preparation method according to claim 1, characterized in that, The swelling treatment temperature is 50-80℃, and the swelling treatment time is 1-5 minutes.

5. The preparation method according to claim 1, characterized in that, In step S3, the alkaline solution is an inorganic alkaline solution, an organic alkaline solution, or a mixed solution of inorganic and organic alkalines.

6. The preparation method according to claim 5, characterized in that, The alkaline solution has a mass concentration of 5-95 wt%, the alkaline hydrolysis treatment temperature is 50-80℃, and the immersion time is 1-5 min.

7. The preparation method according to claim 5, characterized in that, The inorganic base is one or more of sodium hydroxide and potassium hydroxide.

8. The preparation method according to claim 5, characterized in that, The organic base is one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

9. The preparation method according to claim 1, characterized in that, In step S4, the mass concentration of the dilute hydrochloric acid is 10-15 wt%, and the dilute hydrochloric acid immersion treatment time is 1-5 min.

10. The preparation method according to claim 1, characterized in that, The preparation method includes the following steps: Step 1: Provide a surface-modified base LCP film, wherein the upper surface of the base LCP film is coated with a circuit layer; Step 2: Provide a surface-modified intermediate LCP film and stack it on the bottom LCP film. Then, heat-press the stacked bottom LCP film and intermediate LCP film under heating and pressure conditions to form a composite. Step 3: Electroplating a circuit layer on the upper surface of the intermediate LCP film after hot pressing and bonding; Step 4: A surface-modified surface LCP film is laminated on the upper surface of the intermediate LCP film with the circuit layer. The laminated bottom LCP film, intermediate LCP film and surface LCP film are hot-pressed under heating and pressure to obtain an LCP film assembly.

11. The preparation method according to claim 10, characterized in that, The hot pressing is performed under vacuum conditions, with a temperature of 150-300°C, a pressing pressure of 200-400 psi, and a hot pressing time of 30-90 min.

12. The preparation method according to claim 10, characterized in that, Before hot pressing, the LCP film with surface modification is cleaned and dried at a temperature of 80-200℃ for 10-30 minutes.

13. An LCP thin-film module obtained by the preparation method according to any one of claims 1-12, characterized in that, The invention includes a multilayer LCP film bonded by hot pressing, wherein no adhesive is contained between any two adjacent LCP film layers, and the interface region between any two adjacent LCP film layers forms a homogenized molecular-level bonded layer through melt recrystallization and functional group bonding.

14. The application of the preparation method according to any one of claims 1-12 in the preparation of LCP thin film probe cards.

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