A preparation process of a non-contact chip antenna module of a metal strip-based smart card

Abstract

The application belongs to the technical field of antenna module manufacturing, and is especially a preparation process of a smart card non-contact chip antenna module based on a metal strip, comprising the following steps: providing a metal strip as a base material; punching a positioning hole on the metal strip; performing chemical cleaning; pasting a dry photoresist film; performing exposure treatment; S6. developing the exposed metal strip; performing chemical etching; removing the dry film layer; cleaning and drying; roughening treatment; local area electroplating; pressing an insulating encapsulating glue, and forming a recess cavity structure for accommodating a chip module at a corresponding position of a chip connecting area; and cutting the wide strip. In the application, the metal strip itself is used as a structural carrier of the antenna, which improves the durability and reliability of the terminal product in harsh environments, the metal substrate ensures the precision of the antenna pattern lines, realizes large-scale manufacturing with high efficiency and high consistency, and significantly reduces the unit production cost.

Description

Technical Field

[0001] This invention belongs to the field of antenna module manufacturing technology, specifically relating to a fabrication process for a smart card contactless chip antenna module based on a metal strip. Background Technology

[0002] Existing smart card contactless antenna module manufacturing technology typically uses a process of etching copper foil onto a flexible PET substrate. Due to the low mechanical strength and weak bending and deformation resistance of the substrate itself, the antenna is prone to breakage, deformation, or performance degradation under frequent bending, pressure, or harsh environments such as high and low temperatures and humidity, which seriously affects the durability and service life of the product. However, the process of using printed conductive silver paste has problems such as relatively low conductivity of silver paste, blurred line edges, and poor pattern accuracy and consistency. This results in high antenna resistance, insufficient quality factor, and unstable radio frequency performance, which limits the read and write distance, communication rate and reliability. In particular, it is difficult to meet the strict electrical performance requirements of high frequency and high security level applications. Furthermore, the aforementioned traditional processes often struggle to achieve high-precision graphical positioning and efficient, continuous roll-to-roll automated production, resulting in low production efficiency, difficulty in cost control, and difficulty in ensuring product consistency, thus restricting the demand for large-scale, high-quality manufacturing. Summary of the Invention

[0003] To address the aforementioned problems in the prior art, this invention provides a fabrication process for a smart card contactless chip antenna module based on a metal strip, aiming to solve the technical problems of low mechanical strength and insufficient reliability of antenna structures in the prior art.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a fabrication process for a smart card contactless chip antenna module based on a metal strip, comprising the following steps: S1. Providing a metal strip as a substrate; S2. Continuously punching positioning holes on the metal strip; S3. Chemically cleaning the metal strip with positioning holes; S4. Applying a photoresist dry film to the surface of the cleaned metal strip; S5. Exposing the metal strip with the dry film applied using a mask with a preset chip pattern; S6. Developing the exposed metal strip to form a patterned resist layer; S7. Chemically etching the developed metal strip to remove metal not protected by the resist layer, forming a metal chip pattern; S8. Removing the remaining dry film layer on the strip; S9. Cleaning and drying the etched metal chip pattern; S10. Roughening the surface of the metal chip pattern; S11. Electroplating at least a local area of ​​the metal chip pattern; S12. An insulating encapsulating adhesive is pressed onto the surface of the strip, and a cavity structure for accommodating the chip module is formed at the corresponding position in the chip connection area; S13. The wide strip is cut into multiple independent unit strips.

[0005] Furthermore, the material of the metal strip is stainless steel, copper, or an alloy thereof.

[0006] Furthermore, the positioning holes are chain holes, symmetrically distributed along both sides of the strip, used for precise positioning and conveying in continuous roll-to-roll production.

[0007] Furthermore, the photoresist dry film described in step S4 is a negative dry film with a thickness of 10 to 40 μm.

[0008] Furthermore, the chemical etching in step S7 uses ferric chloride etching solution or acidic copper chloride etching solution, and the etching linewidth accuracy is controlled within ±10μm.

[0009] Furthermore, the roughening treatment in step S10 employs chemical roughening or physical sandblasting to make the surface roughness Ra of the metal pattern greater than or equal to 0.5 μm.

[0010] Furthermore, step S11 is a local selective electroplating, the electroplating area is limited to the chip connection end of the metal chip pattern, and the electroplating structure includes first plating a nickel layer and then plating a gold layer, wherein the thickness of the nickel layer is 1 to 8 μm and the thickness of the gold layer is not less than 0.03 μm.

[0011] Furthermore, the insulating encapsulating adhesive mentioned in step S12 is an epoxy resin adhesive, which is hot-pressed to a thickness of 100 to 300 μm, and a cavity for accommodating the chip module is formed in the adhesive layer by a mold during the pressing process.

[0012] Furthermore, the entire process adopts a roll-to-roll production method, and the strip maintains a continuous roll shape after punching until slitting.

[0013] A smart card contactless chip antenna module strip, manufactured by the process described in any one of claims 1 to 9, includes a metal substrate, a metal antenna pattern etched thereon, a locally electroplated enhancement area, and an insulating encapsulation layer covering the surface of the pattern and having a chip receiving cavity.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, the metal strip itself serves as the structural carrier of the antenna, giving the antenna module extremely high resistance to bending, stretching, and deformation. It can withstand the frequent bending, twisting, and even accidental stepping on by the smart card during use, improving the durability of the terminal product and its reliability in harsh environments. The metal substrate provides a stable stage for subsequent precision photolithography etching processes, ensuring that the antenna pattern can achieve micron-level line accuracy and edge clarity. The inherent high conductivity of the metal provides an advantage for the antenna to achieve low resistance and high Q value. The entire process, from punching positioning holes to final slitting, is carried out on a continuous metal strip, which is compatible with automated roll-to-roll production lines. This solves the problems of inaccurate transmission and positioning and slow production cycle caused by insufficient strength in traditional sheet production or flexible roll materials, achieving high-efficiency and high-consistency large-scale manufacturing and significantly reducing unit production costs.

[0015] 2. In this invention, the surface of the etched metal pattern is roughened, transforming the originally smooth metal surface into a microscopically rough interface. This enables the subsequent epoxy resin adhesive to generate a strong anchoring effect, enhancing the bonding force between the encapsulation layer and the metal antenna. It prevents delamination and cracking of the adhesive layer due to thermal expansion and contraction or mechanical stress, ensuring the absolute sealing and stability of the encapsulation structure during long-term use.

[0016] 3. In this invention, selective electroplating is performed only on the contact area at the antenna end where the chip needs to be connected. The nickel layer acts as a barrier layer to prevent diffusion between the underlying metal and the gold layer. The gold layer provides an oxidation-resistant, low-contact-resistance surface that is easy to solder or bond with conductive adhesive. This ensures low loss, high reliability, and long-term stability of the electrical interconnection between the chip and the antenna, especially suitable for high-frequency signal transmission requirements, and improves the module's storage and lifespan.

[0017] 4. In this invention, by using a pressure roller with a punch during the hot pressing process of the epoxy resin adhesive, the adhesive layer covering and the chip mounting cavity are formed simultaneously in one go. This eliminates additional adhesive or assembly interfaces, making the module structure extremely compact and robust. It can effectively resist the impact of external forces on the chip area, protecting the chip safety. The synchronously formed cavity has extremely high dimensional and positional accuracy, and is precisely aligned with the antenna connection endpoint below. This provides a unified physical benchmark for the subsequent automatic placement of the chip module using a high-precision pick-and-place machine. This enables the chip bonding process to be automated, high-speed, and high-yield, which is a key prerequisite for achieving full automation of back-end production. By combining the protection and shaping functions into one step, the production process is simplified, equipment investment and process control points are reduced, the production cycle is improved, and alignment errors or contamination that may be caused by multiple processing steps are avoided, thereby further improving the overall production efficiency and product consistency. Attached Figure Description

[0018] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] Example 1: Please see Figure 1This embodiment provides the following technical solution: a fabrication process for a smart card contactless chip antenna module based on a metal strip, comprising the following steps: S1. Providing a metal strip as a substrate; S2. Continuously punching positioning holes on the metal strip; S3. Chemically cleaning the metal strip with positioning holes; S4. Applying a photoresist dry film to the surface of the cleaned metal strip; S5. Exposing the metal strip with the dry film applied using a mask with a preset chip pattern; S6. Developing the exposed metal strip to form a patterned resist layer; S7. Chemically etching the developed metal strip to remove metal not protected by the resist layer, forming a metal chip pattern; S8. Removing the remaining dry film layer on the strip; S9. Cleaning and drying the etched metal chip pattern; S10. Roughening the surface of the metal chip pattern; S11. Electroplating at least a local area of ​​the metal chip pattern; S12. An insulating encapsulating adhesive is pressed onto the surface of the strip, and a cavity structure for accommodating the chip module is formed at the corresponding position in the chip connection area; S13. The wide strip is cut into multiple independent unit strips.

[0021] Specifically, metal strips are provided as the substrate; Chain holes for roll-to-roll conveying and positioning are continuously punched on both sides of the metal strip along its length. The metal strip with chain holes is subjected to alkaline degreasing and acid activation cleaning in sequence to remove surface oil and oxide layer, and then dried. A photosensitive dry film is hot-pressed onto the surface of the cleaned and dried metal strip. Using a mask with a pre-set pattern of the connection end of the antenna coil and the chip, the metal strip covered with dry film is selectively exposed; The exposed metal strip is developed to remove the dry film in the unexposed areas, thereby revealing the metal surface that needs to be etched away, forming a patterned resist layer. The strip is immersed in a chemical etching solution to etch away the metal parts that are not protected by the resist layer, forming a raised metal antenna pattern on the metal strip. Remove the remaining dry film layer on the strip after exposure and curing to fully expose the metal antenna pattern; The etched metal antenna pattern is cleaned and dried. The surface of the metal antenna pattern is roughened to increase its surface roughness; Selective electroplating is performed on the end regions of the metal antenna pattern that correspond to the electrical connections of the chip. On the surface of the strip with metal antenna pattern and electroplated area, an insulating encapsulating adhesive layer is pressed by hot pressing, and during the pressing process, a cavity for accommodating the chip module is simultaneously molded in the corresponding area of ​​the chip connection end. The wide strip that has been encapsulated and cavity-formed is then cut into multiple independent narrow strips containing one or more antenna pattern elements.

[0022] Preferably, by using metal strips as the substrate and combining a series of sequential process steps such as punching positioning holes, applying dry film, exposure, development, chemical etching, roughening, local electroplating, laminating insulating adhesive to form cavities, and slitting, a high-strength metal substrate, precision patterning technology, and integrated packaging are organically combined. This provides a smart card antenna module overall solution with high mechanical strength, high precision, and suitability for continuous production, fundamentally overcoming the core defects of traditional flexible substrate antennas, such as fragility, poor electrical performance, and low production efficiency.

[0023] The metal strip is made of stainless steel, copper, or their alloys.

[0024] Specifically, the metal strip is made of stainless steel or copper; the stainless steel is 304 stainless steel with a thickness of 50-150μm, more preferably about 80μm.

[0025] Preferably, by limiting the metal strip material to stainless steel, copper, or their alloys, the high strength, high rigidity, and high conductivity of these metals provide the optimal choice of basic materials for the antenna module in terms of mechanical and electrical performance, ensuring that the product has both excellent structural durability and superior conductivity.

[0026] The positioning holes are chain holes, symmetrically distributed along both sides of the strip, and are used for precise positioning and conveying in continuous roll-to-roll production.

[0027] Specifically, the chain holes are arranged symmetrically and at equal intervals along both sides of the strip, which is used to achieve precise positioning and continuous conveying in all subsequent process steps of roll-to-roll production.

[0028] Preferably, by defining the positioning holes as chain holes symmetrically distributed along both sides of the strip, it can precisely mesh with the sprockets of automated production equipment, realizing high-precision and high-stability material transmission and positioning during the production process, providing a guarantee for all subsequent precision processing steps, and is the key to adapting to high-efficiency roll-to-roll automated production lines.

[0029] In step S4, the photoresist dry film is a negative dry film with a thickness of 10 to 40 μm.

[0030] Specifically, in step S4, the photoresist dry film is a negative dry film with a coating thickness of 10-40 μm, preferably about 25 μm.

[0031] Preferably, by limiting the applied photoresist dry film to a negative dry film and controlling its thickness to 10 to 40 μm, the process window and pattern resolution of exposure and development are optimized, ensuring high precision and high reliability of the photolithography pattern transfer process, and laying the foundation for obtaining micron-level antenna patterns with clear lines and accurate dimensions.

[0032] Step S7 chemical etching uses ferric chloride etching solution or acidic copper chloride etching solution, and the etching linewidth accuracy is controlled within ±10μm.

[0033] Specifically, in step S6, an alkaline solution is used for spray development, and in step S7, ferric chloride etching solution is used for chemical etching to form a metal antenna pattern with a linewidth accuracy within ±10μm.

[0034] Preferably, complex metal patterns can be accurately formed in a controllable and efficient manner, resulting in antenna coil lines with steep edges and good dimensional consistency, which directly determines the accuracy of the antenna inductance and the stability of the radio frequency performance.

[0035] Step S10 roughening treatment uses chemical roughening or physical sandblasting to make the surface roughness Ra of the metal pattern greater than or equal to 0.5 μm.

[0036] Specifically, step S10 roughening treatment is achieved through chemical or physical methods to make the surface roughness of the metal pattern Ra≥0.5μm, so as to significantly enhance its adhesion to the subsequent insulating encapsulation adhesive layer.

[0037] Preferably, by chemically roughening or physically sandblasting the surface of the metal chip pattern to achieve a surface roughness Ra≥0.5μm, mechanical interlocking conditions are created, enhancing the physical bonding between the insulating encapsulation material and the metal antenna pattern, and avoiding reliability issues caused by poor interface bonding, such as adhesive layer peeling, sealing failure, or environmental corrosion.

[0038] Step S11 is a local selective electroplating, the electroplating area is limited to the chip connection end of the metal chip pattern, the electroplating structure includes first plating a nickel layer and then plating a gold layer, wherein the thickness of the nickel layer is 1 to 8 μm and the thickness of the gold layer is not less than 0.03 μm.

[0039] Specifically, in step S11, selective electroplating is performed on the contact area at the connection ends of the two chips in the metal antenna pattern. First, a layer of nickel with a thickness of 1-8 μm is electroplated as a barrier layer, and then a layer of gold with a thickness of not less than 0.03 μm is electroplated on the nickel layer as a solderable and connecting layer.

[0040] Preferably, while ensuring cost-effectiveness, the performance of the electrical connection point between the antenna and the chip is significantly optimized. This area has excellent solderability, low contact resistance, and high resistance to oxidation and corrosion, thereby ensuring low signal transmission loss and long-term connection reliability.

[0041] Step S12 uses epoxy resin as the insulating encapsulant, which is applied by hot pressing to a thickness of 100 to 300 μm. During the pressing process, a cavity for accommodating the chip module is formed in the adhesive layer using a mold.

[0042] Specifically, in step S12, the insulating encapsulating adhesive is epoxy resin; preferably, epoxy resin in the B-Stage state is used, and it is pressed by a hot press roller with a punch, with an adhesive layer thickness of 100 to 300 μm, preferably about 200 μm, and the cavity is integrally formed during the hot pressing process.

[0043] Preferably, it integrates protection, insulation, and structural forming, which not only simplifies the process but also results in a compact and high-strength package structure. It also provides a precise and fixed-position space for subsequent chip mounting, significantly improving the automation and precision of subsequent assembly processes.

[0044] The entire process adopts a roll-to-roll production method, and the strip maintains a continuous roll shape after punching until slitting.

[0045] Specifically, from punching in step S2 to slitting in step S13, the entire process is completed on a continuous roll-to-roll production line, with the strip always being conveyed and processed in roll form.

[0046] The preferred method fully leverages the cost and efficiency advantages of this process in large-scale manufacturing, ensuring high product consistency and stable yield, and meeting the smart card industry's demand for mass production of low-cost, highly reliable core components.

[0047] A smart card contactless chip antenna module strip, manufactured by any one of the processes of claims 1 to 9, includes a metal substrate, a metal antenna pattern etched thereon, a locally electroplated enhancement area, and an insulating encapsulation layer covering the surface of the pattern and having a chip receiving cavity.

[0048] Specifically, its structure includes: a metal substrate, a metal antenna pattern formed on the metal substrate by etching, an electroplated enhancement area disposed at the chip connection end of the metal antenna pattern, and an insulating encapsulation layer covering the metal antenna pattern and part of the surface of the metal substrate and having a chip receiving cavity; the position of the chip receiving cavity corresponds precisely to the electroplated enhancement area.

[0049] Preferably, it provides direct protection for the specific product form obtained by the aforementioned unique process, constructing a dual protection barrier of "method patent" and "product patent", thereby enhancing the protection of patent rights and market exclusivity.

[0050] Example 2: Please see Figure 1In this embodiment, the staff used the device disclosed in this invention in a contactless smart card antenna module project for public transportation tickets in a certain city.

[0051] Workers use a 330mm wide, 80-micron thick roll of 304 stainless steel as the base material, loading it onto a high-precision multi-station stamping machine, such as the AK series servo stamping feeding system from Jacobs. At the first station, the stamping machine continuously punches 2mm diameter circular chain positioning holes at 4mm intervals along both edges of the stainless steel strip. These holes engage with the sprockets at each station in all subsequent processes, ensuring a positioning accuracy within ±15 microns even at belt speeds exceeding 50 meters per minute.

[0052] The punched strip then enters a continuous chemical cleaning line. First, it is immersed for 30 seconds in an alkaline degreasing agent bath at 60 degrees Celsius to remove rolling oil. Next, it is immersed for 20 seconds in an activation bath containing a 5% sulfuric acid solution to remove the surface oxide layer. Finally, it undergoes two stages of deionized water spraying and hot air drying to complete the cleaning and drying process. The clean and dry strip immediately enters a fully automatic laminating machine manufactured by Zhisheng Industrial. This machine uses a pair of pressure rollers heated to 80 degrees Celsius to hot-press a 25-micron thick negative photoresist dry film, such as Asahi Kasei's PFR series dry film, onto the stainless steel strip surface under constant tension.

[0053] The roll of material coated with dry film is fed into an exposure station under a yellow safe light environment, using a German Heidegger UV exposure machine with a light source wavelength of 365 nanometers. The strip is flattened on a vacuum adsorption platform, and a high-resolution glass mask with a precision antenna pattern descends and comes into close contact with the dry film. The pattern on the mask includes a rectangular antenna coil with an outer dimension of approximately 45 mm by 76 mm and a linewidth of 150 micrometers. The coil is connected to square connecting pads measuring 1 mm by 1 mm at both ends. The exposure machine exposes the material at an energy of 100 millijoules per square centimeter, causing the dry film in the area of ​​the connecting pads and the coil pattern to crosslink and cure.

[0054] After exposure, the strip enters the developing section, where it is sprayed with a 1% sodium carbonate solution at 30 degrees Celsius. The dry film in the unexposed areas is dissolved, revealing the stainless steel surface to be etched away, forming a clear patterned resist layer. Next, the strip enters the etching tank, which contains a ferric chloride etching solution at 45 degrees Celsius. The exposed stainless steel portions are etched away by spraying, reaching a depth of 80 micrometers, thus forming a raised, fine antenna pattern on the stainless steel substrate.

[0055] The etched strips then enter the stripping process, where a 4% sodium hydroxide solution is sprayed at 45 degrees Celsius to completely peel off the cured dry film. The strips then undergo another deionized water cleaning and drying process. Next comes the crucial surface treatment process: the strips pass through a chemical roughening tank containing a mixed solution of sulfuric acid and ammonium persulfate at 50 degrees Celsius for 60 seconds. This process increases the surface roughness Ra of the stainless steel antenna pattern to 0.8 micrometers, significantly increasing the bonding area for subsequent encapsulation materials. After roughening, the strips are cleaned and dried.

[0056] The strip then enters a localized electroplating station equipped with a customized localized masking fixture with windows that expose only the two antenna connector pads. The strip first passes through a nickel sulfamate plating bath, where it is plated for 2 minutes at a current density of 2 amperes per square decimeter, forming a dense nickel layer approximately 5 micrometers thick as a barrier layer in the connector pad area. Immediately afterwards, without changing the fixture, the strip enters an acidic gold plating bath, where it is plated for 10 seconds at a current density of 0.5 amperes per square decimeter, forming a pure gold layer at least 0.035 micrometers thick on the nickel layer as a solderable layer.

[0057] After final cleaning and drying, the electroplated strip is fed into a crucial encapsulation device: a thermoforming laminator integrating precision punch rollers. Preheated to 80 degrees Celsius, the strip, along with a 200-micron-thick B-grade epoxy resin film (such as Huntsman's Araldite series), passes through a pair of pressure rollers heated to 150 degrees Celsius and operating at 5 MPa. The lower steel rollers are engraved with rectangular recessed punches precisely aligned with the antenna connector pad. During thermoforming, the epoxy resin film is pressed, cured, and tightly adhered to the roughened metal surface. Simultaneously, the punches precisely imprint a 180-micron-deep, 2.5 mm x 2.5 mm square cavity into the resin layer, perfectly enclosing the gold-plated connector pad.

[0058] The wide strips, after being laminated and packaged, are finally guided to a high-precision slitting machine, such as the slitting machine from Hirayama Manufacturing Co., Ltd. in Japan. This machine slits the 330mm wide roll into seven independent narrow strips according to a preset 45mm unit width and then winds them up separately. These unit strips are the final antenna module semi-finished product obtained in this embodiment. Each unit contains a complete antenna coil and a precisely aligned chip mounting cavity. These strips are then fed into a chip mounter, such as those from ASM Pacific Technology, where a non-contact chip module conforming to ISO 7816 standards is automatically mounted into the cavity using conductive adhesive and heat-pressed. After electrical testing and punching, the final inlay product for urban transportation cards is produced. This embodiment fully reproduces the continuous, automated, and high-precision manufacturing process from metal roll to integrated antenna module strip.

[0059] The working principle of this invention is as follows: Step 1: The process begins with a metal strip, which itself serves as the mechanical support and conductor of the antenna. By stamping high-precision chain holes on both sides of the strip, a physical positioning and transmission benchmark is established for all subsequent processes, ensuring precise alignment of each process unit in high-speed roll-to-roll production.

[0060] The second step involves chemically cleaning the metal strip to remove oil and oxide layers, resulting in a clean and activated metal surface. A photoresist dry film is then applied; this dry film acts as a photosensitive protective layer, preparing the surface for the subsequent exposure and development process to precisely transfer the designed antenna pattern onto the metal surface.

[0061] Step 3: Using a photomask with the pre-fabricated antenna pattern, the dry film is selectively exposed, causing a photochemical reaction in specific areas to solidify. After development, the unexposed areas of the dry film are dissolved and removed, exposing the metal areas that need to be etched away, thus forming a negative image of the antenna pattern protected by the solidified dry film on the metal strip. Then, chemical etching is used to dissolve and remove the exposed metal parts, ultimately forming a raised, precision metal antenna coil pattern on the metal strip. This step achieves micron-level high-precision conversion from the design pattern to the actual metal wire.

[0062] Step 4: After removing the remaining dry film, the formed metal antenna pattern is cleaned and roughened. Roughening significantly improves the mechanical adhesion to subsequent packaging materials by increasing the microscopic roughness of the metal surface, preventing delamination. Subsequently, selective electroplating, such as nickel plating followed by gold plating, is performed only at the ends of the antenna coils, i.e., the contact areas that will connect to the chip.

[0063] This electroplated layer serves two purposes: firstly, it acts as a solderable and connectable layer, ensuring low-resistance and highly reliable electrical interconnection with the chip module; secondly, the nickel layer acts as a barrier layer, preventing the migration of the underlying metal and ensuring the long-term stability and corrosion resistance of the gold layer.

[0064] Step 5: On the patterned and electroplated strip surface, a layer of epoxy resin is pressed onto it using a hot-pressing method. During the hot-pressing process, a pressure roller with a specific punch not only ensures that the resin layer smoothly covers and firmly adheres to the antenna pattern and metal substrate, achieving insulation and protection, but also simultaneously hot-presses a precise cavity at the location corresponding to the chip connection point. This cavity provides a precisely sized and positioned space for the subsequent automated placement of the chip module, achieving a one-time molding of protection and structure.

[0065] Step 6: Finally, the wide metal strip that has been packaged and cavity-formed is cut into multiple independent narrow strips according to the design width. Each strip can contain one or more antenna elements. These element strips are the antenna module semi-finished products that can be directly used for subsequent fully automated chip mounting, bonding, and testing processes.

[0066] Summary of process principles: The essence of this process is to integrate and manufacture high-frequency antennas and chip mounting structures on a rigid metal carrier. Its working principle is consistently manifested as follows: using metal strips to impart strength, using photolithography and etching to achieve precise patterns, using roughening and electroplating to optimize the interface and electrical performance, and using simultaneous hot pressing to complete the integrated packaging.

[0067] The entire process relies on roll-to-roll production lines to achieve continuous operation, which not only ensures high product consistency, high production efficiency and controllable costs, but also fundamentally solves the systemic defects of traditional flexible antennas such as insufficient strength, poor pattern accuracy and low packaging reliability, providing an advanced process foundation for the large-scale manufacturing of high-performance and high-reliability contactless smart cards.

[0068] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A fabrication process for a smart card contactless chip antenna module based on a metal strip, characterized in that, Includes the following steps: S1. Provide metal strips as the substrate; S2. Positioning holes are continuously punched into the metal strip; S3. Perform chemical cleaning on the metal strip with positioning holes; S4. Apply a photopolymer resist dry film to the cleaned metal strip surface; S5. Expose the metal strip coated with dry film using a mask with a preset chip pattern; S6. Develop the exposed metal strip to form a patterned resist layer; S7. Chemically etch the developed metal strip to remove the metal not protected by the resist layer, forming a metal chip pattern; S8. Remove any remaining dry film layer from the strip; S9. Clean and dry the etched metal chip pattern; S10. Roughen the surface of the metal chip pattern; S11. Electroplating at least a partial area of ​​the metal chip pattern; S12. An insulating encapsulating adhesive is pressed onto the surface of the strip, and a cavity structure for accommodating the chip module is formed at the corresponding position of the chip connection area; S13. Divide the wide strip into multiple independent unit strips.

2. The fabrication process of a smart card contactless chip antenna module based on a metal strip according to claim 1, characterized in that: The metal strip is made of stainless steel, copper, or their alloys.

3. The fabrication process of a smart card contactless chip antenna module based on a metal strip according to claim 1, characterized in that: The positioning holes are chain holes, symmetrically distributed along both sides of the strip, and are used for precise positioning and conveying in continuous roll-to-roll production.

4. The fabrication process of a smart card contactless chip antenna module based on a metal strip according to claim 1, characterized in that: The photoresist dry film described in step S4 is a negative dry film with a thickness of 10 to 40 μm.

5. The fabrication process of a smart card contactless chip antenna module based on a metal strip according to claim 1, characterized in that: The chemical etching in step S7 uses ferric chloride etching solution or acidic copper chloride etching solution, and the etching linewidth accuracy is controlled within ±10μm.

6. The fabrication process of a smart card contactless chip antenna module based on a metal strip according to claim 1, characterized in that: The roughening process described in step S10 uses chemical roughening or physical sandblasting to make the surface roughness Ra of the metal pattern greater than or equal to 0.5 μm.

7. The fabrication process of a smart card contactless chip antenna module based on a metal strip according to claim 1, characterized in that: Step S11 is a local selective electroplating, the electroplating area is limited to the chip connection end of the metal chip pattern, the electroplating structure includes first plating a nickel layer and then plating a gold layer, wherein the thickness of the nickel layer is 1 to 8 μm and the thickness of the gold layer is not less than 0.03 μm.

8. The fabrication process of a smart card contactless chip antenna module based on a metal strip according to claim 1, characterized in that: The insulating encapsulating adhesive mentioned in step S12 is epoxy resin adhesive, which is hot-pressed to a thickness of 100 to 300 μm. During the pressing process, a cavity for accommodating the chip module is formed in the adhesive layer by a mold.

9. The fabrication process of a smart card contactless chip antenna module based on a metal strip according to claim 1, characterized in that: The process adopts a roll-to-roll production method throughout, and the strip maintains a continuous roll shape after punching until slitting.

10. A smart card contactless chip antenna module strip, characterized in that, The smart card contactless chip antenna module fabrication process based on metal strip as described in any one of claims 1 to 9 includes a metal substrate, a metal antenna pattern etched thereon, a local electroplated enhancement area, and an insulating encapsulation layer covering the surface of the pattern and having a chip receiving cavity.

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