Non-contact communication IC sheet

Abstract

To provide a non-contact communication IC sheet that does not require the addition of a separate member such as a reinforcing sheet, is unlikely to crack or peel at a boundary between members even with a normal layer structure, and can be formed as a thin sheet.SOLUTION: A non-contact communication IC sheet has at least a core sheet 2 in which an antenna 4 and an IC module 3 are embedded or laid on its surface, and an exterior sheet 5 that sandwiches the core sheet from both surfaces, wherein the viscoelasticity of the core sheet is different from that of the exterior sheet.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an IC sheet that carries an antenna, an IC chip, etc. for contactless communication with the outside, and in particular to a thin, contactless IC sheet that can reduce the occurrence of defects during manufacturing. [Background technology]

[0002] Contactless IC cards, which have a sheet-like substrate carrying a communication antenna, a control IC chip, and the like, are used in a variety of fields.

[0003] Contactless IC cards are typically made by laminating exterior sheets on both sides of a core layer, which contains an IC module, antenna pattern, electrodes, etc., on a hard resin sheet, and then bonding them together with adhesive, etc. The core layer base material and exterior sheet are made of plastic resin, while the antenna pattern and electrodes are made of metal, and the IC module contains a silicon chip. Because each component is made of a different material, the physical and mechanical properties of each component are different.

[0004] As a result, when thermal or mechanical shocks or fluctuations occur during the manufacturing or transportation process, distortions and stresses occur, particularly near the boundaries of each layer or component. This stress can concentrate at the adhesive (fusion) interface between the core layer (where the IC module is located) and the exterior sheet, causing cracks or breakage. This can then stretch to the outermost layer of the exterior sheet, causing localized peeling of the sheet on the back of the IC module, as shown in Figure 3, or cracks originating from the core layer. This can progress further, causing the back of the IC module to peel off, as shown in the bottom diagram of Figure 3.

[0005] In particular, exterior sheets often contain large amounts of white pigments (mainly inorganic pigments such as titanium oxide) to conceal the IC chips and antenna patterns on the inner layer.However, exterior sheets that have increased their concealment in this way have changed thermal properties and reduced elasticity, making them more susceptible to embrittlement and cracking during the lamination process.

[0006] As a countermeasure, for example, Patent Document 1 discloses an IC card provided with a reinforcing sheet layer that covers at least the boundary between the card substrate and the IC module. However, achieving a configuration like that of Patent Document 1 requires a reinforcing sheet as a separate component, and the reinforcing sheet must be inserted or formed in a separate process, resulting in extra work and cost. Furthermore, inserting the reinforcing sheet creates a new interface, which can lead to peeling.

[0007] It is also possible to apply a protective layer using a roll coater or the like to prevent cracking on the card surface, but when the resin of the protective layer is applied, when the outermost layer is laminated with the same thermoplastic resin sheet as the substrate and processed into a card or data page, the thermoplastic resin sheets cannot be integrated as a single material because a different material is interposed between them, which can easily cause peeling between the sheets.

[0008] Meanwhile, in recent years, there has been an increasing demand for thin, sheet-like contactless communication IC sheets that are thinner than conventional IC cards and can be easily bound into booklets, etc. However, with such thin sheets, it is difficult to add extra sheets for the reinforcement described above, and because they are thin, they are susceptible to fluctuations in thermal and mechanical conditions during manufacturing, making them particularly susceptible to peeling and cracking near the boundaries between the IC module and each sheet component, which have different physical properties.As a result, the sheet can peel off in the IC module area, which is a major problem. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 62-55195 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention aims to provide a non-contact communication IC sheet that can be formed as a thin sheet, does not require the addition of a separate member such as a reinforcing sheet, and is less likely to crack or peel at the boundaries between members even with a normal layer structure. [Means for solving the problem]

[0011] The present invention provides a non-contact communication IC sheet that has at least a core sheet in which an antenna and an IC module are embedded or laid on the surface, and an exterior sheet that sandwiches the core sheet from both sides, and is characterized in that the viscoelasticity of the core sheet is different from that of the exterior sheet. [Effects of the Invention]

[0012] According to the non-contact communication IC sheet of the present invention, even if stress concentrates at the interface of the sheets, the difference in viscoelasticity between the exterior sheet and the core sheet enhances the fusion between the sheets even after lamination, preventing the occurrence of cracks originating at the interface and local peeling. Furthermore, if a sheet with a low flexural modulus is used for the exterior sheet, it is possible to prevent the sheet from cracking even if local stress occurs. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view of one embodiment of the non-contact communication IC sheet of the present invention. [Figure 2] FIG. 2 is a cross-sectional view of the non-contact communication IC sheet of the present invention when deformed. [Figure 3] FIG. 10 is an explanatory diagram of a manner in which peeling occurs in a conventional non-contact communication IC sheet. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiments described below. Furthermore, in the embodiments shown below, technically preferable limitations are imposed for carrying out the invention, but these limitations are not essential requirements for the present invention.

[0015] An embodiment of a contactless communication IC sheet (hereinafter also simply referred to as IC sheet) will be described with reference to FIG. [External configuration of IC sheet] As shown in Figure 1, IC sheet 1 comprises a core sheet 2, an IC module 3, and an antenna 4, which are integrated by laminating with an exterior sheet 5. The thickness is about 250 to 500 µm, which is thinner than a typical plastic card (760 µm), although it is not limited to this.

[0016] [IC sheet internal components] The IC sheet 1 includes an IC module 3 and an antenna 4, and is embedded in the core sheet 2 or laid on its surface. The antenna coil that constitutes the antenna 4 may be an etched antenna in which a pattern is formed by etching a metal foil adhered to a resin film, an embedded coil antenna in which copper wire is embedded in a resin film using ultrasonic waves, or a hollow coil antenna obtained by self-fusing copper wire, but an embedded coil antenna made of copper wire is preferable in consideration of adhesion to the thermoplastic resin described below.

[0017] The IC module 3 may be a bare chip diced from a wafer, or a commercially available standard IC package equipped with a lead frame together with a bare chip, and may be selected appropriately depending on the type of antenna 4 to be adopted, such as a film antenna or a wire coil antenna.

[0018] In this embodiment, a general-purpose IC package module that allows for a wide antenna joint is used. The IC module 3 and antenna 4 can be joined by soldering or thermocompression welding, and the method can be selected depending on durability and the intended use. However, in order to keep the sheet thickness thin, it is desirable to use thermocompression welding to weld the copper wire of the antenna 4 to the lead frame of the IC module 3.

[0019] [Core sheet, exterior sheet] As the core sheet 2 and the exterior sheet 5, synthetic resin sheets are preferably used, for example, polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate copolymer, polyolefin resins such as polyethylene, polypropylene, polymethylpentene, polyethylene fluorinated ethylene resins such as ethylene-tetrafluoroethylene copolymer, polyamides such as nylon 6 and nylon 66, vinyl polymers such as polyvinyl chloride, vinyl chloride / vinyl acetate copolymer, ethylene / vinyl acetate copolymer, ethylene / vinyl alcohol copolymer, polyvinyl alcohol, vinylon, polystyrene, polycarbonate, polyarylate, polyimide, etc., and the materials are selected so that the exterior sheet 5 and the core sheet 2 have different viscoelasticity.

[0020] [Lamination method] The lamination conditions are set appropriately depending on the softening temperature and glass transition point of each resin, and known lamination methods can be appropriately adopted and applied. As an example, in the case of a polycarbonate film, the film is heat-pressed at about 150°C to 190°C and a pressure of about 1 MPa to 15 MPa for about 10 to 30 minutes, and then cooled for 10 to 30 minutes while maintaining the pressure, to complete the lamination.

[0021] When a bending force is repeatedly applied to the IC sheet 1 configured as shown in Figure 2, the IC module 3 made of metal, silicon, etc., and the portions of the resin exterior sheet 5 and core sheet 2 laminated directly above and below the IC module 3 are resistant to deformation, but other portions of the exterior sheet 5 and core sheet 2 are deformed, with the strain concentrated in a region 6 near the boundary with the IC module 3. At this time, particularly strong stress is generated in the exterior sheet 5, but by making the flexural modulus of the exterior sheet 5 different from that of the core sheet 2, it is possible to prevent cracking and peeling of the exterior sheet 5. It is particularly preferable to make the flexural modulus of the exterior sheet 5 lower than that of the core sheet 2. Furthermore, by making the flexural modulus of the exterior sheet 5 less than 2,800 MPa, and further making the flexural modulus of the exterior sheet 5 2,400 MPa or less, cracking and peeling can be made even less likely to occur.

[0022] As explained above, in the IC sheet of the present invention, the core sheet on which the antenna and IC are placed and the exterior sheet attached to the outside of the core sheet have different viscoelastic properties, and in particular the flexural modulus of the exterior sheet is smaller than the flexural modulus of the core sheet. Therefore, when the IC sheet is applied to a medium such as a contactless IC card or passport IC data page that has an information integrated circuit (IC), a coil-type antenna, and a thermoplastic resin sheet and communicates by electromagnetic induction, a highly durable medium can be obtained without parts of the sheet cracking, peeling, or falling off. [Example]

[0023] [Confirmation of effect through bending test] Following the method described above, a bending test was conducted to compare IC sheet A, which used DPI-AW (manufactured by Mitsubishi Chemical) as the core sheet and a polycarbonate sheet with an elastic modulus of 2,400 MPa as the exterior sheet, and IC sheet B, which used DPI-AW (manufactured by Mitsubishi Chemical) as the core sheet and a polycarbonate sheet with an elastic modulus of 2,800 MPa as the exterior sheet. When a 180-degree bending test was conducted with a curvature radius of 15 mm centered on the back of the IC module, no localized cracks occurred in IC sheet A, which used a sheet with an elastic modulus of 2,400 MPa, but localized cracks occurred in the sheet on the back of the IC module in IC sheet B, which used a polycarbonate sheet with an elastic modulus of 2,800 MPa. [Explanation of symbols]

[0024] 1. Contactless communication IC sheet 2...Core sheet 3...IC module 4...Antenna 5...Exterior sheet 6...Area near the boundary

Claims

[Claim 1] A non-contact communication IC sheet comprising at least a core sheet in which an antenna and an IC module are embedded or laid on the surface, and an exterior sheet that sandwiches the core sheet from both sides, wherein the viscoelasticity of the core sheet is different from that of the exterior sheet.

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