An additive production process for radio frequency identification tag antennas

Abstract

The present invention discloses an additive production process for radio frequency identification tag antennas, and belongs to the technical field of radio frequency identification tag antenna production. The production process mainly includes: S1, forming an antenna pattern on an antenna substrate with a heat-resistant adhesive according to the antenna design pattern, and then drying to form a dried uncured adhesive layer, and then spraying a layer of conductive particles on the dried uncured adhesive layer and making it adhere to the dried uncured adhesive layer to form a conductive particle layer; S2, curing the dried uncured adhesive layer with the conductive particle layer; S3, after curing, covering the conductive particle layer with a conductive material to form a conductive material connection layer, so that the conductive material and the conductive particles are combined to form a stable electrical connection between the conductive particles, forming a radio frequency identification tag antenna. The production process avoids the wastewater discharge pollution caused by etching, and also avoids the high cost and unstable performance of the silver paste printed antenna, truly realizing the green and environmentally friendly additive production process of the RF ID antenna, and also provides the possibility for subsequent chip binding by welding instead of ACP glue.

Description

Technical Field

[0001] The invention relates to an additive production process for a radio frequency identification tag antenna, and belongs to the technical field of radio frequency identification tag antenna production. Background Art

[0002] The development process of RFID tag antenna production technology has gone through the process of wire bundling, screen printing etching, gravure etching and conductive silver paste printing. Currently, about 90% of antennas are produced by gravure etching, and some are produced by conductive silver paste printing.

[0003] The following disadvantages exist in the production process using etching technology: (1) Etching and de-inking steps are required, so a large amount of high COD waste liquid needs to be discharged during the production process, and a large amount of waste ink will be generated; (2) Due to the increasing environmental awareness in various places, the site selection of the factory will be subject to many environmental factors, and supporting environmental protection equipment is required, and it is not easy to pass the review; (3) The etching production process is complicated, and the etching process parameters are not easy to detect and control; (4) Heating is required before etching begins, and cooling is required after etching begins, and high-power equipment such as pumps, drying, and acid gas absorption must continue to work, so the etching production process consumes a lot of energy; (5) Etching equipment is generally large and requires a lot of equipment, so it needs to occupy a lot of production space; (6) The selection of the substrate is limited by the etching process and needs to be water-resistant, acid-resistant, and alkali-resistant; (7) Strong acids, strong alkalis, and a large amount of hazardous chemicals such as composite glues, inks, and solvents are required; (8) The utilization rate of raw materials is low; (9) The antenna after etching is prone to adhesion after winding, and additional processing steps are required; (10) Inflammable and explosive hydrogen will be generated during the production process.

[0004] Although the conductive silver paste printing process has certain advantages over the etching process, it also has the following defects: the cost of conductive silver paste materials is very high; the silver paste printed antenna has poor winding and bending resistance; the performance is unstable and easily affected by environmental factors; and it cannot be supplied in large quantities due to cost issues. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides an additive production process for radio frequency identification tag antennas. The production process can focus on solving the shortcomings of the existing etching process and silver paste printing process, has no discharge of wastewater or waste liquid, is energy-saving and green, occupies less production space, has high production capacity, and the prepared products have high performance and reliability.

[0006] The technical solution of the present invention is:

[0007] The present invention discloses an additive production process for a radio frequency identification tag antenna, which mainly includes the following steps:

[0008] S1, forming an antenna pattern on an antenna substrate using a heat-resistant adhesive according to the antenna design pattern, then drying a solvent or a diluent to form a dried uncured adhesive layer, then spraying a layer of conductive particles on the dried uncured adhesive layer and allowing the conductive particles to adhere to the dried uncured adhesive layer to form a conductive particle layer; wherein the diameter of the conductive particles is greater than the film thickness of the dried uncured adhesive layer;

[0009] S2, curing or aging the dried uncured adhesive layer with the conductive particle layer;

[0010] S3, after curing or aging, covering the conductive particle layer with a conductive material connection layer formed by conductive material, so that the conductive material is combined with the conductive particles to form a stable electrical connection between the conductive particles, thereby forming the radio frequency identification tag antenna.

[0011] Its further technical solution is:

[0012] The method of forming the antenna pattern using the heat-resistant adhesive in step S1 is printing or printing.

[0013] Its further technical solution is:

[0014] The heat-resistant adhesive in step S1 is one of solvent-based heat-curing adhesive, water-based heat-curing adhesive, solvent-based UV adhesive, water-based UV adhesive or solvent-based moisture-curing adhesive, and the heat-resistant adhesive can withstand conditions of at least 180° C. / 10 s after curing.

[0015] Its further technical solution is:

[0016] The conductive particles in step S1 are copper powder particles, copper-coated silver powder particles, nickel-coated silver powder particles, and particles with a conductive non-metallic outer layer coated with metal.

[0017] Its further technical solution is:

[0018] The film thickness of the uncured adhesive layer dried in step S1 is 1 / 3 to 2 / 3 of the diameter of the metal particles.

[0019] Its further technical solution is:

[0020] The curing method of drying the uncured adhesive layer in step S2 is one of heat curing, UV curing or moisture curing.

[0021] Its further technical solution is:

[0022] The method of covering the conductive material connection layer in step S3 is at least one of printing, low-temperature sintering, vacuum sputtering, melting, evaporation, electroplating, low-temperature welding, ultrasonic welding, laser sintering and metal compound reduction; the conductive material is one of copper, low-melting point alloy, silver and liquid metal.

[0023] Its further technical solution is:

[0024] When the conductive material is copper, the method of covering the conductive material connection layer in step S3 is:

[0025] Use a printable ink that can reduce copper, and print the ink on the conductive particle layer and between adjacent conductive particles or cover the conductive particles, then reduce the ink, and the reduced metal connects the conductive particles together; or

[0026] A copper layer is sputtered on the conductive particle layer and between adjacent conductive particles by vacuum sputtering.

[0027] Its further technical solution is:

[0028] When the conductive material to be covered is silver, the method of covering the conductive material connection layer in step S3 is:

[0029] The conductive particles in the conductive particle layer are connected together by low-temperature sintering of nano-silver.

[0030] Its further technical solution is:

[0031] When the covered conductive material is a low melting point tin alloy, the method of covering the conductive material connection layer in step S3 is:

[0032] The low melting point alloy is melted and coated, and the molten low melting point alloy is used to infiltrate and fill the gaps between the conductive particles, and the conductive particles are connected together after cooling and solidification; or

[0033] The conductive particle layer printed with low-temperature solder paste is heated to reflow the solder paste by low-temperature soldering, and the molten soft solder is used to penetrate and fill the gaps between the conductive particles to connect the conductive particles together.

[0034] The beneficial technical effects of the present invention are:

[0035] Compared with the etching method, the production process of the present invention does not require etching and deinking processes, does not discharge wastewater, does not produce waste ink from deinking, has very little COD emission, and is environmentally friendly; the production process has low energy consumption, is low-carbon and environmentally friendly; has high production speed and high production capacity; does not require large etching equipment and supporting environmental protection facilities, and requires a small production site; the selection range of substrates is wider than that of aluminum etching antennas, and paper substrates with good temperature resistance can be directly used to make label antennas; does not use strong acids, strong alkalis and anti-corrosion inks, and the amount of adhesives and solvents used is also significantly reduced; the utilization rate of raw materials is high, and the loss is reduced; there is no phenomenon of composite glue re-adhesion that is easy to occur in etching antennas, and no anti-adhesion treatment is required; the production process is relatively simple, and the production process is easy to control;

[0036] Compared with the silver paste printing antenna method, the production process of the present invention has lower raw material costs; the performance of the antenna is more stable and reliable; it provides the possibility of using welding methods to replace ACP glue to bind chips; and no flammable and explosive hydrogen is generated during the production process, thereby improving production safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the antenna structure after the antenna pattern is formed on the antenna substrate using a temperature-resistant adhesive;

[0038] Figure 2 is a schematic diagram of the front structure of the antenna after a conductive particle layer is formed on the dried uncured adhesive layer;

[0039] Figure 3 is a schematic diagram of the back structure of the antenna after a conductive particle layer is formed on the dried uncured adhesive layer;

[0040] Figure 4 It is a schematic diagram of the antenna structure after the conductive particle layer is covered with a conductive material connection layer;

[0041] Figure 5 is a schematic diagram of the antenna structure after the conductive particle layer and the conductive material connecting layer are combined;

[0042] Figure 6 is the overall antenna schematic;

[0043] in:

[0044] 1. Antenna substrate; 2. Drying uncured adhesive layer; 3. Conductive particle layer; 4. Conductive material connecting layer; 5. Tag antenna. DETAILED DESCRIPTION

[0045] In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the specific implementation methods of the present invention are further described in detail below in conjunction with the drawings and examples. The following examples are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0046] The following specific embodiment describes in detail the additive production process of the radio frequency identification tag antenna described in the present application, and the production process mainly includes the following steps:

[0047] S1, forming an antenna pattern on an antenna substrate 1 according to the antenna design pattern using a heat-resistant adhesive, and then drying the moisture or solvent or diluent in the heat-resistant adhesive to form a dried uncured adhesive layer 2, and then spraying a layer of conductive particles on the dried uncured adhesive layer and allowing the conductive particles to adhere to the dried uncured adhesive layer to form a conductive particle layer 3.

[0048] The antenna substrate in the above steps can be a PET substrate or an environmentally friendly paper substrate.

[0049] The heat-resistant adhesive is one of solvent-based heat-curing adhesive, water-based heat-curing adhesive, solvent-based UV adhesive, water-based UV adhesive or solvent-based moisture-curing adhesive, and the heat-resistant adhesive can withstand at least 180°C / 10s after curing. The heat-resistant adhesive selected in this specific embodiment is a commercially available adhesive, such as Rohm and Haas Adcote 502s polyurethane composite adhesive, Coreactant F isocyanate curing agent, etc.

[0050] The method of using the heat-resistant adhesive to form the antenna pattern is printing or printing, and the printing method can be screen printing or other conventional printing methods.

[0051] The conductive particles in the above steps are copper powder particles, copper-coated silver powder particles, nickel-coated silver powder particles, and conductive non-metal-coated metal particles, such as silicon dioxide microparticle-coated silver particles.

[0052] The diameter of the conductive particles is greater than the film thickness of the dried uncured adhesive layer 2, and the film thickness of the dried uncured adhesive layer is preferably 1 / 3 to 2 / 3 of the diameter of the metal particles. In this specific embodiment, the particle size of the conductive particles is preferably 5 μm, and the film thickness of the dried uncured adhesive layer is preferably 2-3 μm. The heat-resistant adhesive can adhere the conductive particles while not completely covering the conductive particles, so that all conductive particles are partially exposed in the dried uncured adhesive layer, which is convenient for subsequent connection through conductive materials.

[0053] S2, curing the dried uncured adhesive layer with the conductive particle layer; the curing method is one of heat curing, UV curing or wet curing, and other common adhesive curing methods can also be used. The specific process parameters such as heat curing temperature or UV curing irradiation energy and irradiation time are the existing technology in the field, which can be known and determined by those skilled in the art according to the type of temperature-resistant adhesive selected, the thickness of the dried adhesive layer and the existing technology in the field, and will not be repeated in this specific embodiment.

[0054] S3, after the uncured adhesive layer is dried and cured, a layer of conductive material is covered on the conductive particle layer to form a conductive material connection layer, so that the conductive material is combined with the conductive particles to form a stable electrical connection between the conductive particles, thereby forming the radio frequency identification tag antenna.

[0055] In the above steps, the conductive material is one of copper, a low melting point alloy, silver and liquid metal, wherein the low melting point alloy is a low melting point tin-based alloy or a low melting point bismuth-based alloy, and the melting point of the low melting point alloy is preferably 138°C; wherein the liquid metal is a gallium indium tin alloy, and the liquid metal is melted by heating to a temperature higher than the melting point (preferably 47-145°C) in a subsequent step, and then formed into a solid by returning to normal temperature or cooling, and forms an alloy with a higher melting point with the conductive particles.

[0056] In the above steps, the method of covering the conductive material connection layer is one of printing, low-temperature sintering, vacuum sputtering, melting, evaporation, electroplating, low-temperature welding, ultrasonic welding, laser sintering and metal compound reduction.

[0057] When carrying out the specific step of combining the conductive material with the conductive particles, the method of covering the conductive material connection layer on the conductive particles and the method of combining the conductive material with the conductive particles are different according to the different conductive materials selected. The specific embodiments of this part are exemplified as follows:

[0058] Embodiment 1:

[0059] When the conductive material to be covered is copper, the method of covering the conductive material connection layer in step S3 is to use a printable ink that can reduce copper element, and print the ink on the conductive particle layer. The ink containing copper ions is reduced to copper element under the action of external conditions and combines with copper conductive particles, and fills the gaps between copper particles to form a continuous conductive layer; or, a copper layer is sputtered on the conductive particle layer by vacuum sputtering, and copper is sputtered into the gaps between adjacent conductive particles, so that all conductive particles can be connected together.

[0060] The copper element reduced from the ink or the copper sputtered by vacuum is used to fill the gaps between the conductive particles, so that the conductive particles are connected to each other to form a dense conductive layer formed by the conductive particles and the connecting material, thereby forming a tag antenna.

[0061] Embodiment 2:

[0062] When the conductive material to be covered is silver, the method of covering the conductive material connection layer in step S3 is to connect the conductive particles in the conductive particle layer together by low-temperature sintering of nanosilver (i.e., low-temperature sintering technology of silver nanoparticles). The nanosilver particles are melted by low-temperature sintering, and the molten silver fills the gaps between the conductive particles. After the silver solidifies, the conductive particles are connected to each other to form a dense conductive layer formed by the conductive particles and the connecting material, thereby forming a tag antenna.

[0063] Embodiment three:

[0064] When the conductive material to be covered is a low-melting-point tin-based alloy, the method of covering the conductive material connection layer in step S3 is to first print a layer of solder paste (such as tin-bismuth alloy solder paste) on the conductive particle layer, and use the fluidity or plasticity of the solder paste to fill the gaps between the conductive particles. Then, the antenna printed with the solder paste is heated by low-temperature soldering to reflow the solder paste, and the molten soft fiber solder is infiltrated to fill the gaps between the conductive particles, and the conductive particles are welded together to form a dense conductive layer composed of conductive particles and soft fiber solder to form a tag antenna.

[0065] Theoretically, the dimensional accuracy of the antenna prepared by this process can be as large as the error of the conductive particle diameter. Taking into account the precision error of glue printing, it can usually be ≤±50μm. The bending resistance and weather resistance are better than those of the usual silver paste printed antenna.

[0066] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An additive production process for radio frequency identification tag antennas, characterized in that: The main steps include: S1, forming an antenna pattern on an antenna substrate using a heat-resistant adhesive according to the antenna design pattern, and then drying to form a dried uncured adhesive layer, and then spraying a layer of conductive particles on the dried uncured adhesive layer and making the conductive particles adhere to the dried uncured adhesive layer to form a conductive particle layer; wherein the diameter of the conductive particles is greater than the film thickness of the dried uncured adhesive layer; and the film thickness of the dried uncured adhesive layer is 1 / 3 to 2 / 3 of the diameter of the metal particles; S2, curing or aging the dried uncured adhesive layer with the conductive particle layer; S3, after curing or aging, covering the conductive particle layer with a conductive material connection layer formed by conductive material, so that the conductive material is combined with the conductive particles to form a stable electrical connection between the conductive particles, thereby forming the radio frequency identification tag antenna.

2. The additive production process of the RFID tag antenna according to claim 1, characterized in that: The method of forming the antenna pattern using the heat-resistant adhesive in step S1 is printing or printing.

3. The additive production process of the RFID tag antenna according to claim 1, characterized in that: The heat-resistant adhesive in step S1 is one of solvent-based heat-curing adhesive, water-based heat-curing adhesive, solvent-based UV adhesive, water-based UV adhesive or solvent-based moisture-curing adhesive, and the heat-resistant adhesive can withstand conditions of at least 180° C. / 10 s after curing.

4. The additive production process of the RFID tag antenna according to claim 1, characterized in that: The conductive particles in step S1 are copper powder particles, copper-coated silver powder particles, nickel-coated silver powder particles, and conductive non-metal-coated metal particles.

5. The additive production process of the RFID tag antenna according to claim 1, characterized in that: The curing method of drying the uncured adhesive layer in step S2 is one of heat curing, UV curing or moisture curing.

6. The additive production process of the RFID tag antenna according to claim 1, characterized in that: The method of covering the conductive material connection layer in step S3 is at least one of printing, low-temperature sintering, vacuum sputtering, melting, evaporation, electroplating, low-temperature welding, ultrasonic welding, laser sintering and metal compound reduction; the conductive material is one of copper, low-melting point alloy, silver and liquid metal.

7. The additive production process of the RFID tag antenna according to claim 6, characterized in that: When the conductive material is copper, the method of covering the conductive material connection layer in step S3 is: A printable ink capable of reducing copper is used, and after the ink is printed on the conductive particle layer and between adjacent conductive particles, the ink is subjected to copper reduction; or a copper layer is sputtered on the conductive particle layer and between adjacent conductive particles by vacuum sputtering.

8. The additive production process of the RFID tag antenna according to claim 6, characterized in that: When the conductive material to be covered is silver, the method of covering the conductive material connection layer in step S3 is: connecting the conductive particles in the conductive particle layer together by low-temperature sintering of nano-silver.

9. The additive production process of the RFID tag antenna according to claim 6, characterized in that: When the covered conductive material is a low-melting-point tin alloy, the method of covering the conductive material connection layer in step S3 is: melt the low-melting-point alloy by melting the low-melting-point alloy, use the molten low-melting-point alloy to penetrate and fill the gaps between the conductive particles, and connect the conductive particles together after cooling and solidification; or use low-temperature welding to heat the conductive particle layer printed with solder paste to reflow the solder paste, and use molten soft solder to penetrate and fill the gaps between the conductive particles to connect the conductive particles together.

Images