Durable rfid tag and method of manufacturing the same

Abstract

The application discloses a durable RFID tag and a manufacturing method thereof. The tag comprises a flexible substrate, a conductive layer arranged on the flexible substrate, and a radio frequency chip electrically connected with the conductive layer. The radio frequency chip is arranged at an edge area of the flexible substrate, and a supporting structure is arranged on a side of the flexible substrate away from the radio frequency chip. The supporting structure forms a supporting area, and a projection of the radio frequency chip in a direction perpendicular to the flexible substrate is located in the supporting area. An annular thin metal layer is further arranged on the flexible substrate and surrounds the supporting structure. By arranging the radio frequency chip at the edge area and forming a low-strain protection area of the chip by using the supporting structure, a graded stress distribution structure is formed in the process of bending the tag, so that the peeling stress and the shearing stress of a connecting area of the chip are reduced, the risk of chip falling off and connection failure is reduced, and the structural reliability and the service life of the RFID tag in a repeated bending, rubbing and washing environment are improved.

Description

Technical Field

[0001] This invention belongs to the field of radio frequency identification and flexible electronic device technology, specifically relating to a durable RFID tag and its manufacturing method. Background Technology

[0002] Radio frequency identification (RFID) tags, especially UHF band tags, have been widely used in logistics, retail, asset management, garment washing, industrial linen management, flexible wearable devices, and smart packaging due to their long-range identification, rapid reading, and batch processing capabilities. In these applications, tags often need to withstand repeated mechanical fatigue, including bending, rubbing, twisting, impact, and the water pressure, temperature changes, and chemical corrosion during washing. Traditional RFID tags fail after only a few dozen or even dozens of mechanical fatigue cycles, severely limiting their lifespan and application scope.

[0003] Most existing RFID tags use single-sided etched aluminum antennas, and their folding resistance is mainly limited by the following reasons:

[0004] (1) Stress concentration at the connection point between the chip and the antenna: The chip is a rigid body, while the antenna substrate is a flexible material. During the bending process, the chip edge will generate high peeling stress, which will cause the solder joint to desolder or the chip to lift up, resulting in an electrical open circuit.

[0005] (2) Aluminum etched antennas are very thin, usually 5-30 µm. During repeated bending and rubbing, stress will be concentrated at the corners of the traces and at the points where the line width changes abruptly. Fatigue cracks often start and propagate from these locations, eventually leading to open circuits.

[0006] Chinese patent application number 201921081079X discloses a bend-resistant label that improves the label's bend resistance by adding a metal foil buffer layer, such as aluminum foil, to the back of the chip. This buffer layer is positioned on the back of the substrate and surrounds or partially surrounds the chip, thus enhancing the support on the back of the chip and reducing stress that could cause cracking of the chip and conductive adhesive. However, this solution only improves the local stress conditions by adding a metal foil buffer layer to the back of the chip. Its main function is to support and buffer the chip area, but it fails to effectively address the problem of conductive path breakage during repeated bending of the overall antenna structure. Furthermore, this metal foil buffer layer is mostly a covering or surrounding layer, without structurally constraining the chip's position.

[0007] Chinese patent application number 2020226948463 discloses a double-sided small electronic tag, including a first carrier and a second carrier adhered to the first carrier. A first antenna and a chip are disposed on the outer surface of the first carrier, with the first antenna connected to the chip. A second antenna is disposed on the outer surface of the second carrier, and the second antenna is connected to the first antenna via a connector that sequentially penetrates the second carrier and the first carrier. By setting the antenna in a double-layer configuration, with the two antenna layers connected by the connector, rapid replacement is possible if one antenna is damaged or needs to be replaced. However, this solution mainly increases inductance through the double-layer antenna structure to improve radio frequency performance, focusing on enhancing signal coupling capability, without addressing the structural reliability of the tag under mechanical fatigue conditions such as repeated bending and crumpling. Furthermore, the two antenna layers are only connected via the connector, without forming a multi-path conduction structure. When a local conductive path breaks, the entire circuit still fails, thus limiting the tag's durability.

[0008] In summary, although existing RFID tags have made some improvements in chip local support or dual-layer antenna structure, they still lack multi-path redundancy design to address the breakage of conductive paths under mechanical fatigue conditions, making it difficult to effectively improve the long-term reliability and durability of tags in repeated bending and washing environments. Summary of the Invention

[0009] To address the problem that existing RFID tags are prone to conductive path breakage and tag failure under mechanical fatigue conditions such as repeated bending, rubbing, and washing, this invention provides a durable RFID tag that improves the reliability and service life of the tag by achieving redundancy and reconstruction of the conductive path through structural design.

[0010] This invention provides a durable RFID tag, comprising:

[0011] A flexible substrate having opposing first and second surfaces;

[0012] A first conductive layer is disposed on the first surface of the flexible substrate to form a first antenna;

[0013] A second conductive layer is disposed on the second surface of the flexible substrate to form a second antenna;

[0014] An RF chip is electrically connected to the first conductive layer and disposed in the edge region of the flexible substrate to reduce stress concentration in the chip area during bending.

[0015] An encapsulation layer encapsulates the flexible substrate, the first conductive layer, the second conductive layer, and the radio frequency chip to form an overall encapsulation structure and provide protection.

[0016] A support structure is provided on one side of the second surface of the flexible substrate and below the radio frequency chip. The support structure has an enclosed support area. The projection of the radio frequency chip in the direction perpendicular to the flexible substrate is completely located within the support area. An annular thin metal layer is provided on the second surface of the flexible substrate. The thin metal layer is arranged around the support structure and covers the outer area of ​​the support area on the plane to improve the local structural strength and electromagnetic performance.

[0017] Preferably, the traces of the first and second antennas adopt a continuous curvature transition structure at the corners to reduce stress concentration and improve fatigue resistance.

[0018] Preferably, the distance between the center of the radio frequency chip and the boundary in at least one boundary direction of the first conductive layer is the minimum design distance, so as to optimize the overall structural layout and reduce the impact of bending.

[0019] Preferably, it further includes at least two conductive connection points that penetrate the flexible substrate and electrically connect the first conductive layer and the second conductive layer; used to achieve electrical connection between the upper and lower conductive layers; wherein, the conductive connection points are distributed along the antenna trace path, and the conductive connection points divide the first conductive layer into several conductive segments; the conductive connection points cooperate with the second conductive layer to make the second conductive layer span between adjacent conductive segments of the first conductive layer, thereby forming a multi-path conduction structure; when any conductive segment of the first conductive layer breaks, the current can form an alternative conduction path bypassing the broken conductive segment through the second conductive layer and the conductive connection points to maintain overall electrical continuity.

[0020] Preferably, at least one parallel structure is provided between the conductive segments. The parallel structure connects the conductive nodes of different conductive segments, so that the conductive segments form a parallel connection relationship. When any conductive segment breaks, the conduction can still be maintained through the parallel structure, thereby further improving the redundancy of the conductive path. The parallel structure is preferably a conductive bridge.

[0021] Preferably, the projection area of ​​the traces of the second conductive layer in the direction perpendicular to the flexible substrate at least partially overlaps with the projection area of ​​the traces of the first conductive layer in the vertical direction.

[0022] The projection area of ​​the traces of the second conductive layer in the direction perpendicular to the flexible substrate completely overlaps with the projection area of ​​the traces of the first conductive layer in the vertical direction.

[0023] Preferably, both the first antenna and the second antenna are aluminum etched antennas with a trace width of ≥1.0 mm, and both the first antenna and the second antenna have a rounded transition at the corner with a radius of ≥0.75 mm.

[0024] Preferably, the distance from the center of the radio frequency chip to the two adjacent edges of the first conductive layer is 1.0 to 10.0 mm.

[0025] Preferably, the flexible substrate is a PET film with a thickness of 0.025–0.15 mm; and the encapsulation layer is a thermoplastic polyurethane film with a thickness of 0.1–0.5 mm.

[0026] Preferably, the support structure is a rigid ring with an inner diameter of 1.0–5.0 mm, an outer diameter of 2.0–10.0 mm, and a thickness of 0.1–0.5 mm.

[0027] Preferably, the conductive communication points are located along the antenna trace path on the left and right sides of the first conductive layer and / or in the RF chip connection area.

[0028] This solution also discloses a method for manufacturing a durable RFID tag, including the following steps;

[0029] S1. Fabrication of a bifacial antenna: On a flexible substrate covered with aluminum foil on both sides, a first conductive layer and a second conductive layer are formed on the first and second surfaces of the flexible substrate respectively by etching process;

[0030] S2, Radio frequency chip mounting; The radio frequency chip is electrically connected to the first conductive layer and disposed in the edge region of the flexible substrate;

[0031] S3. Form a conductive communication structure; between the first conductive layer and the second conductive layer, at least two conductive communication points are formed by riveting or pressing processes to achieve electrical connection between the upper and lower conductive layers.

[0032] S4. Support structure installation: A rigid circular support structure is provided below the second conductive layer. The support structure is fixed by adhesive. The center of the support structure is arranged coaxially with the center of the RF chip.

[0033] S5. Packaging and molding: After completing the RF chip mounting, conductive connection point formation and support structure installation, the flexible substrate, the first conductive layer, the second conductive layer, the RF chip and the support structure are encapsulated by a hot-press lamination process to form a durable RFID tag.

[0034] Preferably, in step S1, at least one parallel structure is formed in the antenna trace path of the first conductive layer and / or the second conductive layer by etching or printing processes.

[0035] The advantages of this invention are:

[0036] 1. This solution reduces stress concentration transmitted to the chip area by placing the RF chip in the edge region of the flexible substrate and setting the chip center close to the boundary in at least one direction. This effectively reduces the peeling stress and shear stress at the connection between the chip and the conductive layer during bending, reduces the risk of chip warping or falling off, and significantly improves the stability and lifespan of the chip connection.

[0037] 2. This solution involves setting a rigid circular support structure under the RF chip, ensuring that the chip projection is entirely within the support area. This creates a localized low-strain zone in this area during bending, thereby limiting local deformation of the flexible substrate, effectively reducing stress concentration in the chip area, and improving the overall bending fatigue resistance of the label.

[0038] 3. This solution optimizes the antenna trace width and corner structure, increasing the trace width and using a continuous curvature transition structure at the corners. This reduces the stress concentration factor of the conductive layer during bending, making the stress distribution more uniform, delaying the initiation and propagation of fatigue cracks, and improving the fatigue resistance of the conductive layer.

[0039] 4. This solution divides the first conductive layer into multiple conductive segments by setting multiple conductive communication points between the first conductive layer and the second conductive layer, and uses the second conductive layer to form a bridging path. When any conductive segment breaks, an alternative conductive path can still be formed through the second conductive layer and the conductive communication points, thereby maintaining the continuity of electrical connection between the RF chip and the antenna, realizing the conductivity redundancy of the structure, and improving the failure resistance.

[0040] 5. This solution establishes a conductive bridge structure between conductive sections, creating a parallel connection between conductive paths. This further enhances the multi-path conduction structure on top of the existing cross-layer redundancy, transforming the conductive path from single-path transmission to multi-path transmission. Even in the event of local damage or breakage, stable conduction can still be maintained, thereby significantly improving the reliability and durability of RFID tags in complex operating environments. Attached Figure Description

[0041] Figure 1 This is a side view of the label structure of the present invention.

[0042] Figure 2 This is an exploded structural diagram of the present invention.

[0043] Figure 3 This is a structural diagram of the radio frequency chip of the present invention.

[0044] Figure 4 This is a schematic diagram of the optimized structure of the first conductive layer of the present invention.

[0045] Figure 5 This is a schematic diagram of the optimized structure of the second conductive layer of the present invention.

[0046] Figure 6 This is a flowchart illustrating the label manufacturing process of the present invention.

[0047] In the figure: 1 Flexible substrate, 2 First conductive layer, 3 Second conductive layer, 4 Radio frequency chip, 5 Conductive communication point, 6 Encapsulation layer, 7 Support structure, 8 Support area, 9 Parallel structure, 10 Thin metal layer. Detailed Implementation

[0048] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0049] In the description of this invention, it should be noted that the terms "upper", "lower", "inner", "outer", "front end", "rear end", "both ends", "one end", "the other end", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0050] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connected" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Simultaneously, when an component is referred to as "fixed to" or "equipped with" another component, it can be directly on the other component or may have an intervening component present. When an component is referred to as "connected to" another component, it can be directly connected to the other component or may have an intervening component present. When an component is referred to as "fixedly connected to" another component, it can be a common fixed connection method such as welding, bolting, or gluing. In summary, those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0051] Example 1, as Figure 1-3 As shown, a durable RFID tag is described in this embodiment. This embodiment mainly addresses the problem that the radio frequency chip 4 is prone to stress concentration and connection failure under repeated mechanical fatigue conditions. The arrangement position of the radio frequency chip 4 in the tag is optimized.

[0052] The durable RFID tag in this embodiment includes a flexible substrate 1, a first conductive layer 2 and a second conductive layer 3 disposed on both sides of the flexible substrate 1, and an RF chip 4 electrically connected to the first conductive layer 2. The first conductive layer 2 is disposed on the first surface of the flexible substrate 1 to form a first antenna. The second conductive layer 3 is disposed on the second surface of the flexible substrate 1 to form a second antenna.

[0053] The flexible substrate 1 is preferably a PET film, which has good flexibility and fatigue resistance. There is also a flexible surface material, namely the encapsulation layer 6, that wraps the flexible substrate 1, the first conductive layer 2, the second conductive layer 3, and the RF chip 4. The flexible surface material is preferably a thermoplastic polyurethane film.

[0054] The radio frequency chip 4 is disposed on the first conductive layer 2 and is integrally arranged in the edge region of the flexible substrate 1. Preferably, the distance between the center position of the radio frequency chip 4 and the boundary in at least one boundary direction of the first conductive layer 2 is the minimum design distance, while in other directions it is not less than the minimum design distance.

[0055] The above arrangement reduces the stress concentration transmitted to the RF chip 4 area when the label experiences mechanical fatigue, thereby reducing the peeling stress and shear stress at the connection between the RF chip 4 and the conductive layer, reducing the risk of the RF chip 4 warping or falling off, and improving the bending fatigue resistance of the overall structure.

[0056] To verify the rationality of the aforementioned edge arrangement, a relationship model between chip position and fatigue life was established, and a differential evolution algorithm was used for position optimization analysis and verification. Differential evolution is a population-based global optimization algorithm that efficiently searches for the optimal solution in a continuous space by simulating the mutation, crossover, and selection mechanisms in biological evolution. The optimization objective function should include at least parameters reflecting mechanical durability and can be comprehensively optimized in conjunction with antenna RF performance parameters.

[0057] Specifically, first, let's define the length and width of the first antenna as A and B, respectively, in mm. Then, the distance from the RF chip 4 to the four edges of the antenna is:

[0058]

[0059] The fatigue life (duty cycles) N of the 4-connection point of the RF chip is inversely proportional to the minimum edge distance:

[0060]

[0061] Since RF chip 4 cannot be placed infinitely close to the edge, space must be reserved for antenna traces and bonding process allowances. Let the minimum allowable design distance for the center of RF chip 4 be... (Typically 1-4mm, depending on the design), then the feasible area is:

[0062]

[0063] Maximizing the number of mechanical fatigue cycles is equivalent to maximizing the objective function:

[0064]

[0065] Within the feasible region, F reaches its maximum value at the boundary (because the smaller the denominator, the larger the function value). Iterative analysis of the objective function shows that as the position of the RF chip 4 gradually approaches the edge region of the first conductive layer 2, the objective function value gradually increases, indicating that the edge region is more conducive to improving the fatigue life of the connection point of the RF chip 4.

[0066] Differential evolutionary algorithm is a population-based global optimization algorithm suitable for non-smooth, non-differentiable objective functions. Here, it is used to search for... The largest ( ).

[0067] Set the following algorithm parameters:

[0068] (1) Dimension of variables: D=2

[0069] (2) Population size: NP=30 (usually 5-10 times the dimension of the variable)

[0070] (3) Scaling factor: F=0.8 (controls the amplitude of differential perturbation)

[0071] (4) Crossover probability: CR=0.9 (controls the proportion of the experimental vector inherited from the mutated vector)

[0072] (5) Maximum number of iterations: (Usually convergent enough)

[0073] (6) Boundary: ,

[0074] The algorithm steps are as follows:

[0075] (1) Initialization: Generate NP individuals uniformly and randomly within the feasible region:

[0076]

[0077] (2) Mutation: For each target vector Randomly select three distinct individuals , , Generate the mutation vector:

[0078]

[0079] If a component goes out of bounds, it is either truncated or regenerated using the boundary value.

[0080] (3) Cross: For each dimension With probability The test vector is obtained by inheriting from the mutation vector or from the target vector. :

[0081]

[0082] in The dimensions are randomly selected, ensuring that at least one dimension comes from the mutated vector.

[0083] (4) Selection: Compare the objective function values ​​of the experimental vector and the target vector, and select the better one to enter the next generation:

[0084]

[0085] (5) Termination: Repeat steps (2)-(4) until the maximum number of iterations is reached. Or it may satisfy other convergence conditions.

[0086] Due to the objective function If the region is convex (more precisely, quasi-convex) within the feasible region, and the maximum value lies on the boundary, the differential evolution algorithm will quickly push the population towards the boundary. After final convergence, the population of all individuals... and They will be distributed in the following four candidate regions:

[0087] (Left edge)

[0088] (Right edge)

[0089] (Bottom edge)

[0090] (Top edge)

[0091] Furthermore, since the objective function only depends on the minimum distance, as long as the RF chip 4 satisfies at least one directional distance of... And the distance in other directions is not less than The function values ​​are all equal (all are...). Therefore, the optimal solution forms a rectangular bounding box (i.e., the boundary of the feasible region). During the iteration process of the differential evolution algorithm, the population gradually converges towards the edge region, verifying the design idea that placing the RF chip 4 in the edge region can effectively reduce bending stress concentration. Therefore, the theoretical optimal solution lies on the boundary of the feasible region, that is, the distance in at least one direction is equal to... .

[0092] From an engineering perspective, corner points (such as...) are usually chosen. This is because placing the chip close to the edge in both directions can further reduce the combined stress during multi-axis bending. However, if the antenna design requires placing the chip at the midpoint of an edge (e.g., for RF matching), theoretically superior bending performance can still be achieved. Figure 3 As shown, based on the analysis results of the differential evolution algorithm and the actual antenna layout requirements, this embodiment places the RF chip 4 in the upper left edge region of the first conductive layer 2, so that the distance from the chip center to the two adjacent edges is the minimum design distance. In this embodiment, the distance from the chip center to the two adjacent edges of the first conductive layer 2 is 1.0 to 10.0 mm, preferably 2 mm.

[0093] Through the above-mentioned position optimization, the local stress borne by the radio frequency chip 4 under conditions such as repeated bending, rubbing or washing of the tag is significantly reduced, thereby effectively extending the fatigue life of the chip connection point and improving the overall durability of the RFID tag.

[0094] Example 2 provides a durable RFID tag, which is further optimized based on Example 2. It mainly addresses the problems of local stress concentration and welding area peeling failure caused by the large difference in stiffness between the RF chip 4 and the flexible substrate 1 during repeated bending. By setting the support structure 7 and the annular thin metal layer 10, the stress distribution in the chip area is optimized, thereby improving the tag's bending resistance and long-term reliability.

[0095] like Figure 2 and Figure 5 As shown, in this embodiment, the durable RFID tag includes a flexible substrate 1, a first conductive layer 2 and a second conductive layer 3 disposed on both sides of the flexible substrate 1, and an RF chip 4 electrically connected to the first conductive layer 2. A support structure 7 is disposed on the second surface of the flexible substrate 1, and the support structure 7 is located below the RF chip 4.

[0096] The support structure 7 is preferably a ring structure, i.e. a rigid ring structure, which encloses the support area 8. The projection of the RF chip 4 in the direction perpendicular to the flexible substrate 1 is entirely located within the support area 8, and preferably the center of the RF chip 4 is coaxially arranged with the center of the rigid ring.

[0097] Through the above structural design, when the label bends, the support structure 7 can preferentially bear the bending load from the flexible substrate 1, forming a relatively stable low-strain region inside the support area 8, while bending deformation mainly occurs in the outer area of ​​the support structure 7. Since the RF chip 4 is entirely located within the support area 8, the relative deformation between the chip body and the flexible substrate 1 is significantly reduced, thereby effectively reducing the peel stress and shear stress borne by the chip and conductive layer connection area, reducing the risk of chip warping, detachment, or solder joint failure, and improving the structural stability of the chip connection area.

[0098] An annular thin metal layer 10 is disposed on the second surface of the flexible substrate 1. The thin metal layer 10 surrounds the support structure 7 and covers the outer area of ​​the support region 8. Preferably, the coverage area of ​​the thin metal layer 10 is larger than the outer contour of the support structure 7, so that it can still cover the surrounding area of ​​the support structure 7 within the range of installation error.

[0099] When there is a significant stiffness difference between the supporting structure 7 and the flexible substrate 1, bending loads can easily create stress abrupt change regions at the edges of the supporting structure 7, leading to new fatigue damage areas near the edges of the supporting structure. To address this, this embodiment uses an annular thin metal layer 10 to create an annular transition region between the supporting region 8 and the surrounding flexible region. When the label bends, the annular thin metal layer 10 allows the local bending stiffness to change gradually, thereby mitigating abrupt changes in stress transmission and transforming the bending strain from a concentrated distribution to a gradual distribution, reducing stress concentration at the edges of the supporting structure 7.

[0100] Meanwhile, the annular thin metal layer 10 can also form a planar constraint on the outer area of ​​the support structure 7, suppressing local warping and bulging deformation during repeated bending, rubbing or washing, improving the overall stability of the structure around the chip area, and thus further enhancing the fatigue resistance of the label.

[0101] Furthermore, since the support structure 7 can be made of different materials such as FR4, polyimide, ceramic, or metal, different materials may have a certain impact on the electromagnetic field distribution near the chip. The annular thin metal layer 10 can equalize the electromagnetic environment around the chip area, reduce the electromagnetic performance fluctuations caused by the change in the material of the support structure 7, and thus improve the consistency of RF performance between different batches of products.

[0102] In this embodiment, the support structure 7 and the annular thin metal layer 10 are not independently configured, but rather work together. The support structure 7 constructs a low-strain protection region for the RF chip 4, limiting local deformation of the chip area. The annular thin metal layer 10 forms a stress transition region between the low-strain region and the surrounding flexible region, reducing stress concentration caused by abrupt changes in stiffness. Together, they create a hierarchical stress distribution structure of "low-strain region – stress transition region – flexible deformation region" when the tag is bent. This effectively reduces the risk of fatigue damage to the chip area and the edges of the support structure, improving the structural reliability and service life of the RFID tag under repeated bending, industrial washing, and long-term use.

[0103] In this embodiment, the support structure 7 is preferably made of a rigid material, such as FR4, polyimide, ceramic, or metal. The preferred dimensions of the rigid ring are: an inner diameter of 2 mm, an outer diameter of 3 mm, and a thickness of 0.3 mm, so that the support structure 7 can effectively cover the chip area without excessively increasing the overall thickness of the label or affecting its flexibility.

[0104] Example 3 provides a durable RFID tag, which is further optimized based on Example 1. It mainly addresses the problem that the conductive layer is prone to fatigue fracture during repeated mechanical fatigue. By optimizing the antenna wiring structure and combining it with the conductive redundancy path design, the risk of fracture is reduced while ensuring the continuity of electrical connection after structural failure, thereby significantly improving the overall durability of the tag.

[0105] like Figure 4 and Figure 5 As shown, the durable RFID tag in this embodiment includes a flexible substrate 1 and a first conductive layer 2 and a second conductive layer 3 respectively disposed on both sides of the flexible substrate 1. The first conductive layer 2 and the second conductive layer 3 respectively form a first antenna and a second antenna. An RF chip 4 is electrically connected to the first conductive layer 2 and disposed in the edge region of the flexible substrate 1; at least two conductive communication points 5 penetrate the flexible substrate 1 and electrically connect the first conductive layer 2 and the second conductive layer 3; an encapsulation layer 6 encapsulates the flexible substrate 1, the first conductive layer 2, the second conductive layer 3, and the RF chip 4.

[0106] In this embodiment, both the first and second antennas are aluminum etched antennas, and the traces of both antennas adopt a continuous path structure. A continuous curvature transition structure is used at the corners to avoid stress concentration caused by right angles or sharp corners. Preferably, the corners are rounded transition structures with a radius of not less than 0.75 mm, and more preferably 0.75 mm.

[0107] The trace width of the first and second antennas is not less than 1.0 mm, and preferably 1.5 mm. By increasing the trace width, the stress concentration of the conductive layer during mechanical fatigue can be reduced, thereby delaying the initiation of fatigue cracks.

[0108] To accommodate different aspect ratios, the first conductive layer 2 uses a common bent dipole structure, which is compact, easy to match, and can be adapted to labels of different sizes by adjusting the size and number of bends.

[0109] To analyze the impact of different antenna structural parameters on mechanical durability and radio frequency performance, a parameter analysis model can be established. The parameters to be analyzed include:

[0110] Antenna trace width (mm), range (Limited by etching process)

[0111] Corner radius (mm), range (0 represents a right angle)

[0112] Dipole arm length (mm), range

[0113] Number of bends, range

[0114] Local linewidth (mm) of the chip connection area, range

[0115] Constraints: The entire antenna must be located in Within the rectangle, and the center of the chip is located in the edge region (according to previous conclusions, the distance from the edge...). ).

[0116] To verify the impact of the wide linewidth and rounded corner transition structure on mechanical durability and RF performance in this embodiment, a comprehensive performance analysis model can be established. Here, a weighted sum form is adopted, and the fitness function is defined as follows:

[0117]

[0118] in:

[0119] Mechanical durability index (the higher the better)

[0120] Reflectance coefficient (dB), the lower the better.

[0121] Radiation efficiency (0-1), the higher the better.

[0122] Weighting coefficients are set according to design priorities (e.g., larger values ​​are used for durability priority). )

[0123] Fatigue fracture of aluminum etched antennas under repeated bending mainly occurs in stress concentration areas: corners and abrupt changes in linewidth. A stress concentration factor is used. and nominal bending stress To estimate relative fatigue life.

[0124] Since abrupt changes in linewidth can be avoided in advance through design, the approximate formula for the stress concentration factor at corners is:

[0125] (Applicable to rounded corners, when) )

[0126] Assuming the label has a bending radius during bending... If the value is fixed, then the maximum bending stress of the aluminum layer is:

[0127]

[0128] in The elastic modulus of aluminum is 70 GPa. This refers to the thickness of the aluminum layer (a fixed value, such as 0.03mm). Actual It's uncertain, but we can compare only the stress concentration multiples of different designs; therefore, the mechanical durability index can be defined as:

[0129]

[0130] Regarding the antenna size parameters given by the differential evolution algorithm, we can use electromagnetic simulation software for a more comprehensive analysis to determine which set of parameters can balance stress and radio frequency performance.

[0131] The specific process is as follows:

[0132] Set the following algorithm parameters:

[0133] (1) Population size: NP=50

[0134] (2) Scaling factor: F=0.7

[0135] (3) Crossover probability: CR = 0.9

[0136] (4) Maximum number of iterations: .

[0137] The optimization steps are as follows:

[0138] (1) Initialization: Randomly generate within the feasible region Group design variables and ensure geometric constraints (such as , wait).

[0139] (2) Fitness assessment: For each individual, mechanical indicators are calculated. Call the electromagnetic model to calculate and Then, the weighted fitness is calculated.

[0140] (3) Mutation and crossover: Experimental vectors are generated using the DE / rand / 1 / bin strategy.

[0141] (4) Selection: If the fitness of the experimental vector is better than that of the current individual, then replace it.

[0142] (5) Termination: The maximum algebra or fitness convergence is reached.

[0143] After iterative analysis of different parameter combinations using the differential evolution algorithm, it was found that the optimal structural parameters typically exhibit the following characteristics:

[0144] (1) Line width Take the larger value (e.g.) mm).

[0145] (2) Corner radius Take the maximum allowed value (e.g.) mm).

[0146] The above analysis results are consistent with the design concept of using a wide line width and rounded corner transition structure in this embodiment, verifying the rationality of the parameter range setting of this structure.

[0147] Combination Figure 5 In this embodiment, the routing of the second conductive layer 3 is similar to that of the first conductive layer 2, except that it is disconnected at the location of the RF chip 4 to accommodate the annular thin metal layer 10. Furthermore, the projection areas of the routing of the first conductive layer 2 and the second conductive layer 3 in the vertical direction at least partially overlap. The routing profile of the second conductive layer 3 can be a scaled-down or reduced version of the routing profile of the first conductive layer 2. By locally reducing or shrinking the size of the second conductive layer 3, it can meet the requirements of bridging and conducting while adapting to the avoidance needs of the chip layout area or other structural components, thereby improving the flexibility of the overall structural layout and reducing the impact of interlayer electromagnetic coupling on RF performance to a certain extent.

[0148] In a preferred embodiment, the trace profile of the second conductive layer 3 is exactly the same as or similar to the trace profile of the first conductive layer 2, so that the first conductive layer 2 and the second conductive layer 3 are basically consistent in structure, thereby achieving a high degree of consistency arrangement, which is conducive to forming a more complete cross-layer redundant conductive path and improving the continuity and stability of the conductive path.

[0149] In this embodiment, at least two conductive communication points 5 are provided, penetrating the flexible substrate 1, and electrically connecting the first conductive layer 2 and the second conductive layer 3. Figure 1 and Figure 3 As shown. The conductive communication points 5 are distributed along the antenna trace path, dividing the first conductive layer 2 into several conductive segments. The conductive communication points 5 cooperate with the second conductive layer 3, so that the second conductive layer 3 spans between adjacent conductive segments of the first conductive layer 2.

[0150] With the above structure, when any conductive segment of the first conductive layer 2 is broken, the current can pass through the second conductive layer 3 and the conductive communication point 5 to form a conduction path that bypasses the broken segment, thereby maintaining the continuity of electrical connection between the RF chip 4 and the antenna.

[0151] Specifically, the first conductive layer 2 and the second conductive layer 3 are electrically connected through several conductive connection points 5. Each conductive connection point 5 can be located at any position, short-circuiting the corresponding points of the upper and lower layers. In this way, the entire system forms a two-layer network. When a section of the upper layer breaks, the current can: (1) enter the second conductive layer 3 from the conductive connection point 5 before the break point of the first conductive layer 2; (2) bypass the break area along the line of the second conductive layer 3; (3) return to the first conductive layer 2 from the conductive connection point 5 after the break point and continue to be transmitted. Therefore, as long as there are connection points on both sides of the break area of ​​the first conductive layer 2 and the second conductive layer 3 is intact in the corresponding section, the system can continue to work.

[0152] The purpose of setting at least two conductive communication points 5 is to ensure that the current can form a closed loop after passing through the first conductive layer 2, the second conductive layer 3, and the conductive communication points 5. Therefore, setting at least two conductive communication points 5 is fundamental. Theoretically, increasing the number of times the tag can be used can increase the number of times it can be used, but the cost will also increase. Therefore, the number and location distribution of conductive communication points 5 need to be balanced between conductivity redundancy and manufacturing cost. Preferably, in this embodiment, the number of conductive communication points is set to three, and the three conductive communication points 5 are set along the antenna trace path on the left and right sides of the first conductive layer 2 and the connection area of ​​the RF chip 4.

[0153] To analyze the impact of different conductive connection point 5 arrangements on tag reliability, a conductivity reliability analysis model can be established. To simplify the analysis, the antenna is considered as a main path consisting of several line segments connected in series, starting from one pad of the RF chip 4, passing through each segment to reach another pad (forming a loop). In reality, UHF antennas are mostly balanced structures, but we can consider all the traces between the feed points as a series chain.

[0154] Let the total length of the antenna trace be Divide it into equal parts Segments, each segment is [length missing] . No. The segment has a failure probability density The probability depends on the stress level of that segment (such as line width, corner radius, and distance from the edge). According to fatigue theory, the cumulative failure probability... It follows a Weibull distribution or another distribution. During the analysis, the focus is on the number of bends at a fixed number. The probability that the segment remains intact is as follows:

[0155]

[0156] The failure probability of a certain segment is related to the degree of stress concentration. Based on the previous DE analysis, the failure probability is higher at the corners of the stress concentration region. We can set the failure probability of each segment as:

[0157]

[0158] in The characteristic lifetime is related to the segment's location. For simplicity, we use the normalized failure probability. To characterize.

[0159] To facilitate the analysis of different layout schemes for conductive communication points 5, this scheme adopts an interval redundancy model. The specific steps are as follows:

[0160] (1) Number the traces of the first conductive layer 2 in sequence as segments. .

[0161] (2) Suppose that the conductive communication point 5 divides the first conductive layer 2 into several intervals. Each interval consists of a continuous segment between two adjacent communication points (or endpoints).

[0162] (3) For each interval, if the first conductive layer 2 breaks in the interval, as long as the second conductive layer 3 is intact in the interval and there are conductive communication points 5 (or endpoints connected to the chip) at both ends of the interval, the current can bypass the break point through the second conductive layer 3.

[0163] More precisely, the survival condition of the system is that for any break point in the first conductive layer 2, there exists a path from one side of the chip to the other side, which may be partly in the first conductive layer 2 and partly in the second conductive layer 3, and all segments passed through (including the first conductive layer 2 and the second conductive layer 3) are intact.

[0164] To evaluate the effect of conductive connection point 5 on improving overall reliability, the following reliability evaluation model can be established:

[0165] (1) =Single-layer antenna (without second conductive layer (3) redundancy) in The probability of survival after a bend (i.e., the probability that all segments are intact, because it is a series system).

[0166] (2) =Double layer plus communication points (number of communication points) ,Location The probability of survival after the same number of bends.

[0167] The probability of increasing the number of bends is defined as:

[0168]

[0169] maximizing Meanwhile, the constraint of the number (cost) of conductive communication points (5) is also considered. Therefore, a fitness function can be defined:

[0170]

[0171] in This is the cost weight of each communication point (which can be set according to the complexity of the process). Alternatively, we can... Also used as a variable for direct optimization Then choose a solution with an acceptable cost.

[0172] Set the number of communication points Fixed (or treated as an integer variable, requiring handling of discreteness). The location of each communication point is determined by the arc length coordinates along the antenna trace. This indicates that the variable vector is:

[0173]

[0174] For simplicity, assume that the communication point is only set on the path of the upper layer wiring (the corresponding position in the lower layer is naturally connected).

[0175] To verify the rationality of different conductive communication point 5 layout schemes, a differential evolution algorithm can be used for iterative analysis. The algorithm parameters can be set as follows:

[0176] (1) Population size: NP=30

[0177] (2) Scaling factor: F=0.8

[0178] (3) Crossover probability: CR = 0.9

[0179] (4) Maximum number of iterations: .

[0180] Perform reliability calculations:

[0181] For each individual (the set of communication points), perform the following steps:

[0182] (1) Discretize the antenna traces into Segment, length of each segment .

[0183] (2) Assign a failure probability to the segment based on its location (whether it is at a corner). (Based on pre-calculated stress distribution).

[0184] (3) Constructing a graph model for a two-layer network:

[0185] Nodes: two pads on the chip, two nodes corresponding to the upper and lower layers for each communication point, and nodes at both ends of each segment.

[0186] Edge: Each segment of the first conductive layer (2) (existence probability) ), the second conductive layer (3) segments (with the same probability, the second layer is considered to be basically the same as the first layer and there is no chip, but it is also affected by fatigue and has the same failure probability), the conductive communication point (5) edge (considered as an ideal connection, but it can also be assumed to have a small probability of failure).

[0187] (4) Calculate the connectivity probability from source to sink using recursive decomposition or based on minimum path set. .

[0188] (5) Calculation ,in .

[0189] (6) Return fitness (If cost is taken into consideration).

[0190] (7) Update the population according to the standard mutation, crossover, and selection strategy of the differential evolution algorithm until convergence.

[0191] Analysis results show that when conductive communication points 5 are located on both sides of areas with a high probability of failure, an effective bypass conduction path can be formed after a break occurs in the corresponding area, thereby significantly improving the overall reliability of the tag. Therefore, conductive communication points 5 should be arranged on both sides of areas with a high probability of failure as much as possible so that when these areas break, the current can bypass through the lower layer. As the number of communication points increases, The number of conductive communication points gradually increases, but with diminishing marginal returns. Once all major weak areas are covered, adding more communication points offers little improvement in reliability. Further analysis reveals that as the number of conductive communication points 5 increases, tag reliability gradually improves, but the rate of improvement gradually decreases. Once the major weak areas are covered, further increasing the number of conductive communication points 5 offers limited improvement in reliability. A typical UHF antenna consists of approximately 10 segments connected in series, each with a failure probability... Differences (e.g., higher probability of failure at both ends). Calculation Then, the optimal communication point layout is found through DE, and calculations are performed. ,get The analysis results show that only 2-3 communication points are needed to significantly increase the survival probability from 1.2% to 64%-89%, which is the most cost-effective. After more than 4 points, the marginal benefit drops sharply. This result verifies the rationality of setting the number of conductive communication points 5 in this embodiment.

[0192] Example 4 is a durable RFID tag, which is further optimized based on Example 3. It mainly addresses the problem that the single-path conductive structure has the risk of failure under complex bending or local damage. By introducing a parallel conductive structure in the conductive layer, a multi-path conductive network is constructed, thereby further improving the conductive reliability and failure resistance of the tag.

[0193] like Figure 4 As shown, in this embodiment, the durable RFID tag includes a flexible substrate 1 and a first conductive layer 2 and a second conductive layer 3 disposed on both sides of the flexible substrate 1. The first conductive layer 2 and the second conductive layer 3 respectively form a first antenna and a second antenna. In the wiring path of the first conductive layer 2, the original series conductive path is divided into several conductive segments.

[0194] At least one parallel structure 9 is set between adjacent conductive sections. The parallel structure 9 is a conductive bridge. The parallel structure 9 connects the conductive nodes of different conductive sections, so that the conductive sections form a parallel connection relationship, thereby forming at least one alternative conductive path in addition to the original main conductive path.

[0195] Through the above-mentioned parallel structure 9 design, when a certain conductive section in the first antenna breaks due to bending fatigue or external force damage, the current can bypass the broken section through the parallel structure 9 and continue to be transmitted in other conductive paths, thereby maintaining the overall conductivity continuity and ensuring the normal communication function between the RF chip 4 and the antenna.

[0196] The parallel structure 9 is preferably located near high-stress areas of the antenna trace path, such as trace corners or chip connection areas, to improve the conduction redundancy at critical locations.

[0197] In some implementations, the parallel structure 9 can be integrally formed with the conductive layer by etching or printing processes, or it can be set by attaching or welding independent conductive materials to meet the manufacturing requirements under different process conditions.

[0198] To verify the rationality of the number and location of the parallel structure 9, a conduction reliability analysis model can be established.

[0199] During the analysis, the two feed point chip pads of the antenna are used as the start and end nodes, and all trace segments and parallel structures form a graph network. Each trace segment is assigned a probability. Maintaining conductivity, the parallel structure 9 is considered ideally conductive or given an extremely low failure probability. System survival probability. Defined as the probability that there is at least one connected path from the start node to the end node. Calculated using Monte Carlo simulation. And design the following variables:

[0200] (1) Number of parallel structures

[0201] (2) The position of each parallel structure 9 is determined by the arc length coordinates along the antenna trace. express

[0202] Therefore, calculate the maximum system survival probability. Considering the cost of parallel structure 9, the fitness is defined as follows:

[0203]

[0204] in Cost coefficient for each parallel structure 9.

[0205] To verify the rationality of different parallel structure 9-position schemes, a differential evolution algorithm can be used for iterative analysis. The algorithm parameters can be set as follows:

[0206] (1) Population size: NP=40

[0207] (2) Scaling factor: F=0.8

[0208] (3) Crossover probability: CR = 0.9

[0209] (4) Maximum number of iterations:

[0210] (5) Variable boundaries: and satisfy (Achieved through sorting)

[0211] Optimization steps:

[0212] (1) Initialization: Randomly generate within the feasible region Group Positions (for fixed) ).

[0213] (2) Fitness assessment: For each set of locations, a graph network is constructed, and Monte Carlo simulation is used to calculate the fitness. And calculate fitness.

[0214] (3) Mutation and crossover: The DE / rand / 1 / bin strategy is used to generate test vectors, and the position coordinates are mutated and crossed while maintaining the sorting constraints.

[0215] (4) Selection: retain individuals with higher fitness.

[0216] (5) Iteration: until convergence, output the optimal position and the corresponding .

[0217] Analysis results show that introducing parallel structures 9 into a single-layer antenna can form an alternative conductive path when a local conductive path breaks, thereby significantly improving the conductive reliability of the tag under repeated bending conditions. Further analysis revealed that only 2-3 parallel structures 9 are needed to increase the system survival probability after 50 bends from 1.2% to 50%-80%, verifying the rationality of the number of parallel structures 9 in this embodiment. This scheme has a simple process, negligible cost in aluminum etched antennas, and greatly contributes to improved durability.

[0218] In practical applications, by introducing the aforementioned parallel conductive structure, the conductive path is transformed from a single transmission path into a multi-path network structure. Combined with the cross-layer redundant path formed by the conductive connection point 5, a multi-dimensional conductive redundancy system can be further constructed, thereby significantly improving the stability and lifespan of RFID tags in complex operating environments. Simultaneously, a corresponding parallel structure 9 can also be introduced into the second conductive layer 3, which can provide greater redundancy to the original mesh structure without increasing additional costs, and more effectively address the risk of wiring breakage in the first and second conductive layers.

[0219] Example 5, as Figure 6 As shown, this embodiment provides a method for manufacturing a durable RFID tag, specifically including the following steps:

[0220] First, in step S1, a dual-sided antenna is fabricated. On a flexible substrate 1 with aluminum foil on both sides, a first conductive layer and a second conductive layer are formed on the first and second surfaces of the flexible substrate using an etching process, thereby forming a dual-sided antenna structure.

[0221] Subsequently, in step S2, the radio frequency chip 4 is mounted. The radio frequency chip 4 is electrically connected to the first conductive layer 2 and placed in the edge region of the flexible substrate 1 to optimize the overall layout and reduce the stress impact on the chip area during bending.

[0222] Next, a conductive communication structure is formed in step S3. At least two conductive communication points 5 are formed between the first conductive layer 2 and the second conductive layer 3 by riveting or pressing to achieve electrical connection between the upper and lower conductive layers, thereby constructing a cross-layer conductive structure.

[0223] Then, in step S4, the support structure is installed. A rigid annular support structure 7 is provided below the second conductive layer 3 and fixed by adhesive. The center of the support structure 7 is arranged coaxially with the center of the RF chip 4 to provide structural support for the chip area.

[0224] Finally, encapsulation is performed in step S5. After the RF chip 4 is mounted, the conductive connection point 5 is formed, and the support structure 7 is installed, the flexible substrate, the first conductive layer 2, the second conductive layer 3, the RF chip 4, and the support structure 7 are encapsulated as a whole using a flexible face material and a hot-press lamination process to form a durable RFID tag.

[0225] In this embodiment, preferably, in step S1, two parallel conductive bridge structures are formed between the antenna traces of the first conductive layer 2 and the second conductive layer 3 by etching or printing processes to improve the redundancy and stability of the conductive path.

[0226] Embodiments of the present 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 durable RFID tag, characterized in that, include: Flexible substrate (1) has a first surface and a second surface opposite to each other; A first conductive layer (2) is disposed on the first surface of the flexible substrate (1) to form a first antenna; A second conductive layer (3) is disposed on the second surface of the flexible substrate (1) to form a second antenna; The radio frequency chip (4) is electrically connected to the first conductive layer (2) and disposed in the edge region of the flexible substrate (1); The encapsulation layer (6) encapsulates the flexible substrate (1), the first conductive layer (2), the second conductive layer (3), and the radio frequency chip (4). A support structure (7) is provided on one side of the second surface of the flexible substrate (1) and below the radio frequency chip (4). The support structure (7) has a support area (8) formed by enclosure. The projection of the radio frequency chip (4) in the direction perpendicular to the flexible substrate (1) is completely located within the support area (8). A thin annular metal layer (10) is provided on the second surface of the flexible substrate (1). The thin metal layer (10) is arranged around the support structure (7) and covers the outer area of ​​the support area (8) on the plane.

2. The durable RFID tag according to claim 1, characterized in that: The traces of the first and second antennas adopt a continuous curvature transition structure at the corners.

3. The durable RFID tag according to claim 1, characterized in that: The center of the radio frequency chip (4) is at least one boundary distance from the boundary of the first conductive layer (2) in at least one boundary direction, which is the minimum design distance to reduce stress concentration during bending.

4. The durable RFID tag according to claim 2, characterized in that: It also includes at least two conductive communication points (5), which penetrate the flexible substrate (1) and electrically connect the first conductive layer (2) and the second conductive layer (3). The conductive communication points (5) are distributed along the antenna trace path. The conductive communication points (5) divide the first conductive layer (2) into several conductive segments. The conductive communication points (5) cooperate with the second conductive layer (3) so that the second conductive layer (3) spans between adjacent conductive segments of the first conductive layer (2). When any conductive segment of the first conductive layer (2) breaks, the current can pass through the second conductive layer (3) and the conductive communication points (5) to form a conduction path that bypasses the broken conductive segment.

5. The durable RFID tag according to claim 4, characterized in that: At least one parallel structure (9) is provided between the conductive sections. The parallel structure (9) connects the conductive nodes of different conductive sections, so that the conductive sections form a parallel connection relationship. When any conductive section breaks, it can still maintain conduction through the parallel structure (9).

6. The durable RFID tag according to claim 1, characterized in that: The projection area of ​​the traces of the second conductive layer (3) in the direction perpendicular to the flexible substrate (1) at least partially overlaps with the projection area of ​​the traces of the first conductive layer (2) in the vertical direction.

7. The durable RFID tag according to claim 6, characterized in that: The projection area of ​​the traces of the second conductive layer (3) in the direction perpendicular to the flexible substrate (1) completely overlaps with the projection area of ​​the traces of the first conductive layer (2) in the vertical direction.

8. The durable RFID tag according to claim 2, characterized in that: Both the first and second antennas are aluminum etched antennas with trace widths ≥1.0 mm. Both the first and second antennas have rounded transitions at corners with a radius ≥0.75 mm.

9. The durable RFID tag according to claim 3, characterized in that: The distance between the center of the radio frequency chip (4) and the two adjacent edges of the first conductive layer (2) is 1.0 to 10.0 mm.

10. The durable RFID tag according to claim 1, characterized in that: The flexible substrate (1) is a PET film with a thickness of 0.025 to 0.15 mm; the encapsulation layer (6) is a thermoplastic polyurethane film with a thickness of 0.1 to 0.5 mm.

11. The durable RFID tag according to claim 1, characterized in that: The support structure (7) is a rigid ring with an inner diameter of 1.0 to 5.0 mm, an outer diameter of 2.0 to 10.0 mm, and a thickness of 0.1 to 0.5 mm.

12. The durable RFID tag according to claim 4, characterized in that: The conductive communication points (5) are located on the left and right sides of the first conductive layer (2) and / or the connection area of ​​the radio frequency chip (4) along the antenna trace path.

13. A method for manufacturing a durable RFID tag as described in claim 1, characterized in that: Includes the following steps; S1. Fabricate a double-sided antenna; On a flexible substrate (1) with double-sided aluminum foil, a first conductive layer (2) and a second conductive layer (3) are formed on the first and second surfaces of the flexible substrate (1) respectively by etching process. S2, RF chip (4) mounting; the RF chip (4) is electrically connected to the first conductive layer (2) and disposed in the edge region of the flexible substrate (1); S3. Form a conductive communication structure; between the first conductive layer (2) and the second conductive layer (3), at least two conductive communication points (5) are formed by riveting or pressing to achieve electrical connection between the upper and lower conductive layers. S4. Installation of support structure (7): A rigid circular support structure (7) is provided below the second conductive layer (3). The support structure (7) is fixed by adhesive. The center of the support structure (7) is arranged coaxially with the center of the radio frequency chip (4). S5. Packaging and molding: After completing the mounting of the RF chip (4), the formation of the conductive communication point (5) and the installation of the support structure (7), the flexible substrate (1), the first conductive layer (2), the second conductive layer (3), the RF chip (4) and the support structure (7) are packaged together by the hot pressing lamination process of the encapsulation layer (6) to form a durable RFID tag.

14. The method for manufacturing a durable RFID tag according to claim 13, characterized in that: In step S1, at least one parallel structure (9) is formed in the antenna trace path of the first conductive layer (2) and / or the second conductive layer (3) by etching or printing process.

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