High frequency induction card based on ptfc composite film

Abstract

This invention relates to the field of high-frequency inductive cards, and more particularly to a high-frequency inductive card based on a PTFE composite film. The card includes a card substrate, an inductive antenna encapsulated in the middle of the card substrate, and a chip encapsulation layer. The chip and the inductive antenna are electrically connected. The card substrate, from top to bottom, includes a first conductive shielding layer, a first reinforcing material layer, and a first gradient dielectric-modified PTFE composite film. This invention, by setting a first gradient dielectric-modified PTFE composite film and a second gradient dielectric-modified PTFE composite film, both of which are PTFE composite films uniformly filled with ceramic powder and forming a gradient dielectric structure with a gradually decreasing dielectric constant from top to bottom, effectively reduces the reflection and loss of high-frequency signals at the film layer interface, significantly improving read / write distance and signal stability. Simultaneously, the first waterproof and breathable PTFE microporous film layer and the second waterproof and breathable PTFE microporous film layer have low dielectric loss characteristics, further reducing signal transmission attenuation.

Description

Technical Field

[0001] This invention relates to the field of high-frequency induction card technology, and more particularly to high-frequency induction cards based on PTFE composite films. Background Technology

[0002] High-frequency proximity cards (such as smart cards) are widely used in access control, payment, and identity recognition. Their core components are typically made from traditional polymer materials such as PVC (polyvinyl chloride), PET (polyester), or PC (polycarbonate) through a lamination process to form the card substrate, encapsulating the inductive antenna and chip within it. However, as applications expand to high-temperature, high-humidity, strong electromagnetic interference, and harsh outdoor environments…

[0003] Materials such as PVC, PET, and PC have relatively high and unstable dielectric constants and dielectric loss factors. Under high-frequency (13.56MHz and above) operating conditions, signal transmission loss is large, reading and writing distance is shortened, sensitivity is reduced, and communication reliability is difficult to guarantee. In addition, traditional cards have limited resistance to bending and stretching. Repeated use or accidental bending can easily lead to internal antenna breakage or chip desoldering, resulting in a short product life. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a high-frequency induction card based on a PTFE composite film.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A high-frequency induction card based on a PTFE composite film includes a card substrate, an induction antenna and a chip encapsulation layer encapsulated in the middle of the card substrate, and the chip and the induction antenna are electrically connected. The card substrate includes, from top to bottom, a first conductive shielding layer, a first reinforcing material layer, a first gradient dielectric modified PTFE composite film, a first waterproof and breathable PTFE microporous film layer, an induction antenna and chip encapsulation layer, a second waterproof and breathable PTFE microporous film layer, a second gradient dielectric modified PTFE composite film, a second reinforcing material layer, and a second conductive shielding layer. Both the first gradient dielectric-modified PTFE composite film and the second gradient dielectric-modified PTFE composite film are PTFE composite films modified by uniformly filling ceramic powder, and the ceramic powder includes a combination of silicon dioxide, aluminum nitride, and barium titanate; the waterproof and breathable PTFE microporous membrane layer is an expanded PTFE film with a porous mesh structure; and the first conductive shielding layer and the second conductive shielding layer are graphene films. The first and second reinforcing material layers are one of glass fiber woven fabric, polyimide fiber fabric, and aramid fiber nonwoven fabric. The inductive antenna and the chip layer are completely encapsulated between the first waterproof and breathable PTFE microporous membrane layer and the second waterproof and breathable PTFE microporous membrane layer through a hot-pressing composite process.

[0006] Furthermore, the preferred structure is that the first gradient dielectric modified PTFE composite film is a PTFE composite film with a high ceramic powder filling amount, and the ceramic powder mass ratio is 15%-25%; the second gradient dielectric modified PTFE composite film is a PTFE composite film with a low ceramic powder filling amount, and the ceramic powder mass ratio is 5%-12%. The combination of high and low filling amounts forms a gradient dielectric structure with a gradually decreasing dielectric constant from top to bottom. The thickness of the first gradient dielectric modified PTFE composite film and the second gradient dielectric modified PTFE composite film is 8μm-15μm; the thickness of the first waterproof and breathable PTFE microporous membrane layer and the second waterproof and breathable PTFE microporous membrane layer is 20μm-30μm; the thickness of the first reinforcing material layer and the second reinforcing material layer is 10μm-20μm; the thickness of the first conductive shielding layer and the second conductive shielding layer is 1μm-3μm; and the thickness of the card substrate is controlled at 0.7mm-1.0mm.

[0007] Furthermore, in a preferred configuration, the porosity of the first and second waterproof and breathable PTFE microporous membrane layers is 50%-70%, the pore size distribution is 0.1μm-0.5μm, the surfaces are treated with hydrophobic and oleophobic modification, and the contact angle is greater than 110°. The first and second waterproof and breathable PTFE microporous membrane layers, the first and second waterproof and breathable PTFE microporous membrane layers, the first and second gradient dielectric modified PTFE composite membranes, and the second gradient dielectric modified PTFE composite membranes are bonded together without adhesive through a hot-pressing process.

[0008] Furthermore, in a preferred configuration, the first conductive shielding layer and the second conductive shielding layer are composited on the outer surfaces of the first reinforcing material layer and the second reinforcing material layer by a coating process, with a conductivity of not less than 1000 S / cm, and shielding electromagnetic interference in the frequency range of 1MHz-100MHz.

[0009] Furthermore, in a preferred configuration, the first and second reinforcing material layers are uniformly woven glass fiber cloths in the warp and weft directions, with a warp and weft tensile strength of not less than 800 MPa. They are hot-pressed together with the first gradient dielectric modified PTFE composite film and the second gradient dielectric modified PTFE composite film. The surfaces of the first and second reinforcing material layers are subjected to plasma treatment.

[0010] Furthermore, in a preferred configuration, the inductive antenna of the inductive antenna and the chip encapsulation layer is a copper etched antenna with a line width of 0.1mm-0.3mm and a coil turn count of 3-6 turns. The chip of the inductive antenna and the chip encapsulation layer is a high-frequency inductive chip, which is electrically connected to the inductive antenna through conductive adhesive. The connection point is reinforced and hot-pressed. The inductive antenna and the chip encapsulation layer are completely encapsulated inside between a waterproof and breathable PTFE microporous membrane layer and a second waterproof and breathable PTFE microporous membrane layer.

[0011] In addition, the preferred structure is that the edges of the card base are sealed by hot-pressing with PTFE sealing strips, with a sealing width of 1mm-2mm, and the surface of the card base is printed, hot-stamped, and coated.

[0012] A method for preparing a high-frequency induction card based on a PTFE composite film according to any one of claims 1-7, comprising the following steps: S1. Prepare a first gradient dielectric modified PTFE composite film, a second gradient dielectric modified PTFE composite film, a first waterproof and breathable PTFE microporous film layer, a second waterproof and breathable PTFE microporous film layer, a first conductive shielding reinforcement layer, and a second conductive shielding layer respectively. After the three types of film materials pass the performance test, they are cut and used separately. a. The preparation process of the first-gradient dielectric-modified PTFE composite film and the second-gradient dielectric-modified PTFE composite film is as follows: PTFE dispersion resin is ball-milled and mixed with silica and barium titanate ceramic powder, followed by the addition of petroleum ether extrusion aid and silane coupling agent, and then allowed to stand for 12-24 hours at 40℃-60℃; after standing, pre-forming and calendering are performed, with the calendering pressure controlled at 0.5MPa-0.8MPa, and then the calendered strip is placed at 250℃-300℃ for high-temperature degreasing to remove the extrusion aid and achieve film expansion; finally, longitudinal and transverse biaxial stretching is performed at 300℃-350℃, with a longitudinal stretching ratio of 10-20 times and a transverse stretching ratio of 15-25 times, to obtain gradient dielectric-modified PTFE composite films with different filling amounts; b. The first and second waterproof and breathable PTFE microporous membrane layers are made of expanded PTFE resin as raw material. They are formed by extrusion, calendering, high-temperature degreasing and expansion at 250℃-300℃, and biaxial stretching to form a porous network structure. The membrane porosity is controlled at 50%-70%, and the pore size range is 0.1μm-0.5μm. After stretching, the membrane is modified with fluorocarbon hydrophobic and oleophobic properties. c. The first conductive shielding reinforcement layer and the second conductive shielding layer use polyimide fiber cloth as the reinforcement substrate. The substrate surface is first subjected to plasma activation treatment, and then a graphene layer is formed on the surface by coating. The thickness of the conductive layer is controlled between 1μm and 3μm. S2. The induction antenna and the chip packaging layer are pre-positioned. The induction antenna is a copper etched antenna. The chip and the antenna contacts are bonded with high-temperature conductive adhesive and heated and cured at 60℃-80℃ for 10-20 minutes. S3. Following the sequence of the first conductive shielding layer, the first reinforcing material layer, the first gradient dielectric modified PTFE composite film, the first waterproof and breathable PTFE microporous film layer, the induction antenna and chip encapsulation layer, the second waterproof and breathable PTFE microporous film layer, the second gradient dielectric modified PTFE composite film, the second reinforcing material layer, and the second conductive shielding layer, the multilayer film material is precisely stacked and arranged. During the multilayer stacking process, a positioning fixture is used to assist in alignment. Each layer of film material is kept without wrinkles, offsets, or bubbles. After the stacking is completed, the whole thing is placed into a special mold of the hot press to ensure uniform stress and consistent thickness during subsequent hot pressing. S4. The laminated blank is fed into a vacuum hot press and subjected to one-step hot pressing composite under vacuum, high temperature and high pressure conditions. The process parameters for vacuum hot pressing composite are: vacuum degree not lower than -0.09MPa, hot pressing temperature 180℃-230℃, applied pressure 5MPa-15MPa, and hot pressing and holding time 5-15 minutes. A segmented heating and segmented pressurization method is adopted to fully fuse the film materials of each layer into an integrated card substrate. S5. The hot-pressed card blank is subjected to stepped cooling and shaping. Stepped cooling and shaping involves first cooling the card blank to 120°C at a rate of 10°C / min, then naturally cooling it to room temperature, and then die-cutting it into individual cards according to the ISO / IEC7810 standard dimensions. After die-cutting, PTFE sealing strips are used on the edges of the cards, and hot-pressing is performed at 160°C-180°C and 1MPa-3MPa pressure to seal the edges. The sealing width is 1mm-2mm, which improves the edge sealing performance, tear resistance and service life. S6. Perform quality inspection on the die-cut and sealed cards. After all cards pass the inspection, package the finished product to obtain a high-frequency induction card based on PTFE composite film. In addition, the preferred structure is that the detection items in S6 include high-frequency read / write distance, signal stability, bending resistance, waterproof performance, appearance flatness, and high and low temperature resistance.

[0013] The beneficial effects of this invention are as follows: 1. By setting up a first-gradient dielectric-modified PTFE composite film and a second-gradient dielectric-modified PTFE composite film, both of which are PTFE composite films uniformly filled with ceramic powder and forming a gradient dielectric structure with a gradually decreasing dielectric constant from top to bottom, the reflection and loss of high-frequency signals at the film interface are effectively reduced, significantly improving the read / write distance and signal stability. Simultaneously, the first and second waterproof and breathable PTFE microporous film layers have low dielectric loss characteristics, further reducing signal transmission attenuation.

[0014] 2. The first and second conductive shielding layers are made of graphene film with a conductivity of not less than 1000 S / cm. They can shield electromagnetic interference in the 1MHz-100MHz frequency band, prevent external signal crosstalk from affecting reading and writing, and avoid internal signal leakage of the card, thus improving the security of use.

[0015] 3. The first and second reinforcing material layers are made of glass fiber woven fabric with a tensile strength of not less than 800MPa in both the warp and weft directions. After being hot-pressed together with the PTFE composite film, the tensile, bending and tear resistance of the card substrate 01 is significantly improved. It can be repeatedly bent more than 10,000 times without cracking or delamination, effectively protecting the internal antenna and chip and extending the card's service life. Attached Figure Description

[0016] Figure 1 Flowchart for the overall fabrication of a high-frequency induction card; Figure 2 This is a schematic diagram of the structure of a high-frequency induction card; Figure 3 This is a schematic diagram of the structure of a high-frequency induction card after it has been disassembled.

[0017] In the figure: 01, card substrate; 1, first conductive shielding layer; 2, first reinforcing material layer; 3, first gradient dielectric modified PTFE composite film; 4, first waterproof and breathable PTFE microporous film layer; 5, induction antenna and chip encapsulation layer; 6, second waterproof and breathable PTFE microporous film layer; 7, second gradient dielectric modified PTFE composite film; 8, second reinforcing material layer; 9, second conductive shielding layer. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0019] Reference Figure 1-3A high-frequency induction card based on a PTFE composite film includes a card substrate 01, an induction antenna and a chip encapsulation layer 5 encapsulated in the middle of the card substrate 01, and the chip and the induction antenna are electrically connected. The card substrate 01, from top to bottom, includes a first conductive shielding layer 1, a first reinforcing material layer 2, a first gradient dielectric modified PTFE composite film 3, a first waterproof and breathable PTFE microporous film layer 4, an induction antenna and chip encapsulation layer 5, a second waterproof and breathable PTFE microporous film layer 6, a second gradient dielectric modified PTFE composite film 7, a second reinforcing material layer 8, and a second conductive shielding layer 9. Both the first gradient dielectric modified PTFE composite film 3 and the second gradient dielectric modified PTFE composite film 7 are ceramic. A modified PTFE composite membrane is uniformly filled with ceramic powder, which includes a combination of silicon dioxide, aluminum nitride, and barium titanate. The waterproof and breathable PTFE microporous membrane layer 4 is a porous mesh structure expanded PTFE membrane. The first conductive shielding layer 1 and the second conductive shielding layer 9 are graphene films. The first reinforcing material layer 2 and the second reinforcing material layer 8 are one of glass fiber woven fabric, polyimide fiber fabric, and aramid fiber nonwoven fabric. The inductive antenna and the chip layer 5 are completely encapsulated between the first waterproof and breathable PTFE microporous membrane layer 4 and the second waterproof and breathable PTFE microporous membrane layer 6 through a hot-pressing composite process. The graphene film is used to block external electromagnetic interference and ensure stable transmission of high-frequency signals.

[0020] The first waterproof and breathable PTFE microporous membrane layer 4 and the second waterproof and breathable PTFE microporous membrane layer 6 are designed to prevent the antenna and chip from being corroded by external moisture, oil, acid and alkali environments, while reducing high-frequency signal transmission loss.

[0021] Furthermore, the first-gradient dielectric-modified PTFE composite film 3 is a PTFE composite film with a high ceramic powder filling content, where the ceramic powder mass percentage is 15%, and the second-gradient dielectric-modified PTFE composite film 7 is a PTFE composite film with a low ceramic powder filling content, where the ceramic powder mass percentage is 5%. The combination of high and low filling contents forms a gradient dielectric structure with a gradually decreasing dielectric constant from top to bottom. The thickness of both the first-gradient dielectric-modified PTFE composite film 3 and the second-gradient dielectric-modified PTFE composite film 7 is 8 μm. The thickness of the waterproof and breathable PTFE microporous membrane layer 4 and the second waterproof and breathable PTFE microporous membrane layer 6 is 20μm, the thickness of the first reinforcing material layer 2 and the second reinforcing material layer 8 is 10μm, the thickness of the first conductive shielding layer 1 and the second conductive shielding layer 9 is 1μm, and the thickness of the card substrate 1 is controlled at 0.7mm. By combining high and low filler amounts, a gradient dielectric structure with a gradually decreasing dielectric constant from top to bottom is formed, which effectively reduces the reflection and loss of high-frequency signals at the membrane interface and improves the reading and writing distance and signal stability of the inductive card.

[0022] Furthermore, the first waterproof and breathable PTFE microporous membrane layer 4 and the second waterproof and breathable PTFE microporous membrane layer 6 have a porosity of 50% and a pore size distribution of 0.1μm. Their surfaces are treated with hydrophobic and oleophobic modification, and their contact angle is greater than 110°. The first waterproof and breathable PTFE microporous membrane layer 4, the second waterproof and breathable PTFE microporous membrane layer 6, the first gradient dielectric modified PTFE composite membrane 3, and the second gradient dielectric modified PTFE composite membrane 7 are bonded together without adhesive through a hot pressing process. This adhesive-free bonding ensures a tight bond without delamination or bubbles, avoiding the problems of decreased dielectric properties and reduced high-temperature resistance caused by the use of adhesives.

[0023] Meanwhile, the first conductive shielding layer 1 and the second conductive shielding layer 9 are coated onto the outer surfaces of the first reinforcing material layer 2 and the second reinforcing material layer 8, respectively. The conductivity is not less than 1000 S / cm, and the shielding frequency range is 1MHz. This can effectively prevent external signal crosstalk from affecting the normal reading and writing of the induction card, and at the same time prevent the internal signals of the card from leaking outward, thus improving the security of use. The conductive shielding layer and the reinforcing material layer are firmly bonded together, and there is no cracking or falling off after more than 10,000 bends, maintaining stable shielding performance.

[0024] The first reinforcing material layer 2 and the second reinforcing material layer 8 are uniformly woven glass fiber cloths in the warp and weft directions, with a tensile strength of not less than 800 MPa in both directions. They are hot-pressed together with the first gradient dielectric modified PTFE composite film 3 and the second gradient dielectric modified PTFE composite film 7. The surfaces of the first reinforcing material layer 2 and the second reinforcing material layer 8 are plasma treated, which significantly enhances their bonding force with the PTFE composite film. They do not delaminate or debond under high temperature conditions.

[0025] Meanwhile, the inductive antenna and the chip encapsulation layer 5 are copper etched antennas with a line width of 0.1mm and a coil with 3 turns. The inductive antenna and the chip encapsulation layer 5 are high-frequency inductive chips. They are electrically connected to the inductive antenna through conductive adhesive. The connection point is reinforced and hot-pressed. The inductive antenna and the chip encapsulation layer 5 are completely wrapped inside the interior between a waterproof and breathable PTFE microporous membrane layer 4 and a second waterproof and breathable PTFE microporous membrane layer 6.

[0026] Furthermore, the edges of the card substrate 01 are sealed using PTFE sealing strips with a heat-pressed edge width of 1mm. The surface of the card substrate 01 is printed, hot-stamped, and coated to ensure that the internal high-frequency sensing performance is not affected. It is suitable for various application scenarios such as access control, payment, identity recognition, outdoor industrial control, and harsh environment monitoring.

[0027] A method for preparing a high-frequency induction card based on any one of claims 1-7 using a PTFE composite film includes the following steps: S1. Prepare a first gradient dielectric modified PTFE composite film 3, a second gradient dielectric modified PTFE composite film 7, a first waterproof and breathable PTFE microporous film layer 4, a second waterproof and breathable PTFE microporous film layer 6, a first conductive shielding reinforcement layer 1, and a second conductive shielding layer 9 respectively. After the three types of film materials pass the performance test, they are cut and used separately. a. The preparation process of the first gradient dielectric-modified PTFE composite film 3 and the second gradient dielectric-modified PTFE composite film 7 is as follows: PTFE dispersion resin is ball-milled and mixed with silica and barium titanate ceramic powder, followed by the addition of petroleum ether extrusion aid and silane coupling agent, and then allowed to stand at 40°C for 12 hours; after standing, pre-forming and calendering are performed, with the calendering pressure controlled at 0.5 MPa, and then the calendered strip is placed at 250°C for high-temperature degreasing to remove the extrusion aid and achieve film expansion; finally, longitudinal and transverse biaxial stretching is performed at 300°C, with a longitudinal stretching ratio of 10 times and a transverse stretching ratio of 15 times, to obtain gradient dielectric-modified PTFE composite films with different filling amounts; b. The first waterproof and breathable PTFE microporous membrane layer 4 and the second waterproof and breathable PTFE microporous membrane layer 6 are made of expanded PTFE resin as raw material. They are formed by extrusion, calendering, high-temperature degreasing and expansion at 250℃, and biaxial stretching to form a porous network structure. The membrane porosity is controlled at 50% and the pore size range is 0.1μm. After stretching, the membrane is modified with fluorocarbon hydrophobic and oleophobic materials. c. The first conductive shielding reinforcement layer 1 and the second conductive shielding layer 9 use polyimide fiber cloth as the reinforcement substrate. The substrate surface is first subjected to plasma activation treatment, and then a graphene layer is formed on the surface by coating. The thickness of the conductive layer is controlled at 1μm. S2. The induction antenna and the chip packaging layer 5 are pre-positioned. The induction antenna is a copper etched antenna. The chip and the antenna contacts are bonded with high-temperature conductive adhesive and heated and cured at 60°C for 10 minutes. S3. Following the sequence of the first conductive shielding layer 1, the first reinforcing material layer 2, the first gradient dielectric modified PTFE composite film 3, the first waterproof and breathable PTFE microporous film layer 4, the induction antenna and chip encapsulation layer 5, the second waterproof and breathable PTFE microporous film layer 6, the second gradient dielectric modified PTFE composite film 7, the second reinforcing material layer 8, and the second conductive shielding layer 9, the multilayer film material is precisely stacked and arranged. The multilayer stacking process is assisted by a positioning fixture to ensure that each layer of film material is free of wrinkles, offsets, and bubbles. After the stacking is completed, the whole thing is placed in a special mold of the hot press to ensure that the force is uniform and the thickness is consistent during subsequent hot pressing. S4. The laminated blank is fed into a vacuum hot press and subjected to one-step hot pressing composite under vacuum, high temperature and high pressure conditions. The process parameters for vacuum hot pressing composite are: vacuum degree not lower than -0.09MPa, hot pressing temperature 180℃, applied pressure 5MPa, and hot pressing and holding time 5 minutes. A segmented heating and segmented pressurization method is adopted to fully fuse the film materials of each layer into an integrated card substrate 01. S5. The hot-pressed card blank is cooled and shaped in a stepped manner. The stepped cooling and shaping involves first cooling the card blank to 120°C at a rate of 10°C / min, then naturally cooling it to room temperature, and then die-cutting it into individual cards according to the ISO / IEC7810 standard dimensions. After die-cutting, PTFE sealing strips are used on the edges of the cards, and the edges are hot-pressed at 160°C and 1MPa pressure. The sealing width is 1mm, which improves the edge sealing performance, tear resistance and service life. S6. Perform quality inspection on the die-cut and sealed cards. After all cards pass the inspection, package the finished product to obtain a high-frequency induction card based on PTFE composite film. In addition, the S6 tests include high-frequency read / write distance, signal stability, bending resistance, waterproof performance, surface flatness, and resistance to high and low temperatures.

[0028] In this invention, by setting a first gradient dielectric-modified PTFE composite film 3 and a second gradient dielectric-modified PTFE composite film 7, both of which are PTFE composite films uniformly filled with ceramic powder and forming a gradient dielectric structure with a gradually decreasing dielectric constant from top to bottom, the reflection and loss of high-frequency signals at the film interface are effectively reduced, significantly improving the read / write distance and signal stability. Simultaneously, the first waterproof and breathable PTFE microporous film layer 4 and the second waterproof and breathable PTFE microporous film layer 6 have low dielectric loss characteristics, further reducing signal transmission attenuation.

[0029] The first conductive shielding layer 1 and the second conductive shielding layer 9 are made of graphene film with a conductivity of not less than 1000 S / cm. They can shield electromagnetic interference in the 1MHz-100MHz frequency band, prevent external signal crosstalk from affecting reading and writing, and avoid internal signal leakage of the card, thus improving the security of use.

[0030] The first reinforcing material layer 2 and the second reinforcing material layer 8 are made of glass fiber woven fabric with a tensile strength of not less than 800MPa in both the warp and weft directions. After being hot-pressed together with the PTFE composite film, they significantly improve the tensile, bending and tear resistance of the card substrate 01. It can withstand more than 10,000 repeated bends without cracking or delamination, effectively protecting the internal antenna and chip and extending the card's service life.

[0031] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A high-frequency induction card based on PTFE composite film, comprising a card substrate (01), an induction antenna and a chip packaging layer (5) encapsulated in the middle of the card substrate (01), and the chip and the induction antenna are electrically connected, characterized in that, The card substrate (01) comprises, from top to bottom, a first conductive shielding layer (1), a first reinforcing material layer (2), a first gradient dielectric modified PTFE composite film (3), a first waterproof and breathable PTFE microporous film layer (4), an induction antenna and chip encapsulation layer (5), a second waterproof and breathable PTFE microporous film layer (6), a second gradient dielectric modified PTFE composite film (7), a second reinforcing material layer (8), and a second conductive shielding layer (9). The first gradient dielectric modified PTFE composite film (3) and the second gradient dielectric modified PTFE composite film (7) are both PTFE composite films modified by uniform filling of ceramic powder. The ceramic powder includes a combination of silicon dioxide, aluminum nitride and barium titanate. The waterproof and breathable PTFE microporous membrane layer (4) is an expanded PTFE membrane with a porous mesh structure. The first conductive shielding layer (1) and the second conductive shielding layer (9) are graphene films. The first reinforcing material layer (2) and the second reinforcing material layer (8) are one of glass fiber woven fabric, polyimide fiber fabric, and aramid fiber nonwoven fabric. The inductive antenna and the chip layer (5) are completely encapsulated between the first waterproof and breathable PTFE microporous membrane layer (4) and the second waterproof and breathable PTFE microporous membrane layer (6) through a hot-pressing composite process.

2. The PTFE composite film-based high-frequency induction card according to claim 1, characterized by The first gradient dielectric-modified PTFE composite film (3) is a PTFE composite film with a high ceramic powder filling amount, and the ceramic powder mass ratio is 15%-25%. The second gradient dielectric-modified PTFE composite film (7) is a PTFE composite film with a low ceramic powder filling amount, and the ceramic powder mass ratio is 5%-12%. Through the combination of high and low filling amounts, a gradient dielectric structure with a gradually decreasing dielectric constant from top to bottom is formed. The first gradient dielectric-modified PTFE composite film (3) and the second gradient dielectric... The thickness of the electromodified PTFE composite membrane (7) is 8μm-15μm, the thickness of the first waterproof and breathable PTFE microporous membrane layer (4) and the second waterproof and breathable PTFE microporous membrane layer (6) is 20μm-30μm, the thickness of the first reinforcing material layer (2) and the second reinforcing material layer (8) is 10μm-20μm, the thickness of the first conductive shielding layer (1) and the second conductive shielding layer (9) is 1μm-3μm, and the thickness of the card substrate (1) is controlled at 0.7mm-1.0mm.

3. The PTFE composite film-based high-frequency induction card according to claim 1, characterized by The first waterproof and breathable PTFE microporous membrane layer (4) and the second waterproof and breathable PTFE microporous membrane layer (6) have a porosity of 50%-70% and a pore size distribution of 0.1μm-0.5μm. The surfaces are modified with hydrophobic and oleophobic properties and have a contact angle greater than 110°. The first waterproof and breathable PTFE microporous membrane layer (4), the second waterproof and breathable PTFE microporous membrane layer (6), the first gradient dielectric modified PTFE composite membrane (3), and the second gradient dielectric modified PTFE composite membrane (7) are bonded together without glue through a hot pressing process.

4. The PTFE composite film-based high-frequency induction card according to claim 1, characterized by The first conductive shielding layer (1) and the second conductive shielding layer (9) are coated on the outer surfaces of the first reinforcing material layer (2) and the second reinforcing material layer (8) by a coating process. The conductivity is not less than 1000 S / cm, and the shielding frequency range is 1MHz-100MHz electromagnetic interference.

5. The high-frequency induction card based on PTFE composite film according to claim 1, characterized in that, The first reinforcing material layer (2) and the second reinforcing material layer (8) are uniformly woven glass fiber cloths in the warp and weft directions, and the tensile strength in both the warp and weft directions is not less than 800MPa. They are hot-pressed composites with the first gradient dielectric modified PTFE composite film (3) and the second gradient dielectric modified PTFE composite film (7). The surfaces of the first reinforcing material layer (2) and the second reinforcing material layer (8) are plasma treated.

6. The high-frequency induction card based on PTFE composite film according to claim 1, characterized in that, The inductive antenna of the inductive antenna and the chip packaging layer (5) is a copper etched antenna with a line width of 0.1mm-0.3mm and a coil number of 3-6 turns. The chip of the inductive antenna and the chip packaging layer (5) is a high-frequency inductive chip. It is electrically connected to the inductive antenna through conductive adhesive. The connection point is reinforced and hot-pressed. The inductive antenna and the chip packaging layer (5) are completely wrapped inside between a waterproof and breathable PTFE microporous membrane layer (4) and a second waterproof and breathable PTFE microporous membrane layer (6).

7. The high-frequency induction card based on PTFE composite film according to claim 1, characterized in that, The edges of the card base (01) are sealed by hot pressing with PTFE sealing strips, with a sealing width of 1mm-2mm. The surface of the card base (01) is printed, hot stamped, and coated.

8. A method for preparing a high-frequency induction card based on a PTFE composite film according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Prepare a first gradient dielectric modified PTFE composite film (3), a second gradient dielectric modified PTFE composite film (7), a first waterproof and breathable PTFE microporous film layer (4), a second waterproof and breathable PTFE microporous film layer (6), a first conductive shielding reinforcement layer (1), and a second conductive shielding layer (9) respectively. After the three types of film materials pass the performance test, they are cut and ready for use. a. The preparation process of the first gradient dielectric modified PTFE composite film (3) and the second gradient dielectric modified PTFE composite film (7) is as follows: PTFE dispersion resin is ball-milled and mixed with silica and barium titanate ceramic powder, and then petroleum ether extrusion aid and silane coupling agent are added. The mixture is left to stand for 12-24 hours at 40℃-60℃. After standing, pre-forming and calendering are carried out. The calendering pressure is controlled at 0.5MPa-0.8MPa. The calendered strip is then placed at 250℃-300℃ for high-temperature degreasing to remove the extrusion aid and achieve membrane expansion. Finally, the longitudinal and transverse biaxial stretching is carried out at 300℃-350℃. The longitudinal stretching ratio is 10-20 times and the transverse stretching ratio is 15-25 times to obtain gradient dielectric modified PTFE composite films with different filling amounts. b. The first waterproof and breathable PTFE microporous membrane layer (4) and the second waterproof and breathable PTFE microporous membrane layer (6) are made of expanded PTFE resin as raw material. They are formed by extrusion, calendering, high-temperature degreasing and expansion at 250℃-300℃ and biaxial stretching to form a porous network structure. The membrane porosity is controlled at 50%-70% and the pore size range is 0.1μm-0.5μm. After stretching, the membrane is modified with fluorocarbon hydrophobic and oleophobic properties. c. The first conductive shielding reinforcement layer (1) and the second conductive shielding layer (9) are made of polyimide fiber cloth as the reinforcement substrate. The substrate surface is first subjected to plasma activation treatment, and then a graphene layer is formed on the surface by coating. The thickness of the conductive layer is controlled between 1μm and 3μm. S2. The induction antenna and the chip packaging layer (5) are pre-positioned. The induction antenna is a copper etched antenna. The chip and the antenna contacts are bonded with high temperature resistant conductive adhesive and heated and cured at 60℃-80℃ for 10-20 minutes. S3. Following the sequence of the first conductive shielding layer (1), the first reinforcing material layer (2), the first gradient dielectric modified PTFE composite film (3), the first waterproof and breathable PTFE microporous film layer (4), the induction antenna and chip encapsulation layer (5), the second waterproof and breathable PTFE microporous film layer (6), the second gradient dielectric modified PTFE composite film (7), the second reinforcing material layer (8), and the second conductive shielding layer (9), the multilayer film material is precisely stacked and arranged. The multilayer stacking process is assisted by positioning fixtures for alignment. Each layer of film material is kept without wrinkles, offsets, or bubbles. After the stacking is completed, the whole thing is placed in a special mold of the hot press to ensure uniform stress and consistent thickness during subsequent hot pressing. S4. The laminated blank is fed into a vacuum hot press and hot-pressed in one step under vacuum, high temperature and high pressure conditions. The process parameters for vacuum hot-pressing are: vacuum degree not lower than -0.09MPa, hot-pressing temperature 180℃-230℃, applied pressure 5MPa-15MPa, and hot-pressing holding time 5-15 minutes. The segmented heating and segmented pressurization method is adopted to fully fuse the film materials of each layer into an integrated card substrate (01). S5. The hot-pressed card blank is subjected to stepped cooling and shaping. Stepped cooling and shaping involves first cooling the card blank to 120°C at a rate of 10°C / min, then naturally cooling it to room temperature, and then die-cutting it into individual cards according to the ISO / IEC7810 standard dimensions. After die-cutting, PTFE sealing strips are used on the edges of the cards, and hot-pressing is performed at 160°C-180°C and 1MPa-3MPa pressure to seal the edges. The sealing width is 1mm-2mm, which improves the edge sealing performance, tear resistance and service life. S6. Perform quality inspection on the die-cut and sealed cards. After all cards pass the inspection, package the finished product to obtain a high-frequency induction card based on PTFE composite film.

9. The method for preparing a high-frequency induction card based on a PTFE composite film according to claim 8, characterized in that, The testing items in S6 include high-frequency read / write distance, signal stability, bending resistance, waterproof performance, appearance flatness, and resistance to high and low temperatures.

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