METHOD OF FILLING A SLIT IN A METALLIC SMARTCARD

Abstract

A method for filling a through slit in a metal layer for use in a metallic smartcard by providing a metal sheet having at least one through slit extending through the thickness of the metal sheet, applying a polymer resin to the metal sheet so as to substantially fill the slit(s), and curing the resin. A coupling frame for a smartcard, and a smartcard are also provided.

Claims

1. A method for filling a through slit in a metal layer for use in a metallic smartcard, comprising the steps of: (a) providing a metal sheet having at least one through slit extending through the thickness of the metal sheet; (b) applying an electrically insulating polymer resin to the metal sheet so as to substantially fill the at least one slit; and (c) curing said resin.

2. The method of claim 1, wherein said resin comprises a UV or heat-curable urethane resin.

3. The method of claim 2, wherein said metal sheet has a plurality of said through slits located such that, following said curing step, the sheet can be cut so as to provide metal layers sized for individual smartcards, with each smartcard having one of can be cut from the sheet, thereby providing slitted metal layers for multiple smartcards (e.g., 25 cards from one sheet).

4. The method of claim 3, wherein the resin is deposited over the slits from nozzles and, once the resin has substantially filled the slits, the resin is cured by advancing the sheet beneath a UV light.

5. The method of claim 2, wherein said urethane resin comprises a curable resin having high bond strength to the metallic sheet and at least one of the following post-cure properties: Durometer Shore D hardness (ASTM D2240) of 60-95; Tensile strength at break (ASTM D2556) of 15-30 MPa; Modulus of elasticity (ASTM D638) of 300-600 MPa; and Elongation at break (ASTM D638) of 40-150%.

6. The method of claim 5, wherein said urethane resin comprises a curable resin having at least two of said post-cure properties.

7. The method of claim 6, wherein said urethane resin comprises a curable resin having all of said post-cure properties.

8. The method of claim 4, wherein the resin has a viscosity prior to curing of 150-3000 cP at 20 rpm (ASTM D2556).

9. The method of claim 7, wherein the resin has a viscosity prior to curing of 150-3000 cP at 20 rpm (ASTM D2556).

10. The method of claim 9, wherein the metal layer comprises stainless steel and the resin is an acrylated urethane resin.

11. A coupling frame for a smartcard, comprising: (a) a metal layer having an opening or recess for receiving a transponder chip module; (b) a slit extending from the opening or recess to an outer edge of the metal layer; and (c) a urethane resin that fills said slit.

12. A smartcard comprising the coupling frame of claim 11 and a transponder chip located in said opening or recess.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0008] FIG. 1 depicts, in plan view, a slitted metal layer that forms a coupling frame surrounding an opening in which a Chip is located, of a metallic smartcard.

DETAILED DESCRIPTION

[0009] The following detailed description describes examples of embodiments of the invention solely for the purpose of enabling one of ordinary skill in the relevant art to make and use the invention. As such, the detailed description and illustration of these embodiments are purely illustrative in nature and are in no way intended to limit the scope of the invention, or its protection, in any manner.

[0010] Embodiments of the present disclosure provide a method of filling one or more slits formed in a metal layer of a metallic smartcard, particular one or more slits configured such that the metal layer forms at least one coupling frame that at least partially surrounds an opening or recess in which the Chip is located, such that the coupling frame facilitates contactless communication between the smartcard and a reader. The one or more slits extend through the thickness of at least one metal layer of the smartcard, such as from an opening or recess in which the chip is positioned to an edge of the smartcard. The width of the one or more slits can be constant or vary, and can be about 10 μm to about 500 μm, from about 20 μm to about 250 μm, from about 20 μm to about 100 μm, about 10 μm, about 20 μm, about 30 μm, about 40 μm, about 50 μm, about 60 μm, about 70 μm, about 80 μm, or any of the slit widths described in the Finn Publications.

[0011] The method comprises applying an electrically insulating polymer resin to the slitted metal layer for a metallic smartcard so as to substantially fill the slit, and thereafter curing the resin. In some embodiments, the polymer resin comprises an electrically insulating urethane resin, particularly a UV and/or heat-curable urethane resin. In further embodiments, the polymer resin (e.g., a urethane resin) comprises a curable resin having high bond strength to the metallic layer and one or more, two or more, three or more, or all of the following properties (after curing):

TABLE-US-00001 Durometer Shore D hardness (ASTM D2240) 60-95   Tensile strength at break (ASTM D2556)  15-30 MPa Modulus of elasticity (ASTM D638) 300-600 MPa Elongation at break (ASTM D638) 40-150%

[0012] In some embodiments, the polymer resin (e.g., a urethane resin) meeting one, two, three or four of the above post-curing properties has a viscosity (prior to curing) of 150-3000 cP at 20 rpm (ASTM D2556).

[0013] In one particular embodiment, the metal layer comprises stainless steel, and the resin comprises a UV-curable, acrylated urethane resin (e.g., acrylate-terminated urethane oligomer resin), having an uncured viscosity of 150-3000 cP at 20 rpm (ASTM D2556), a durometer Shore D hardness (ASTM D2240) of 60-95, a tensile strength at break (ASTM D2556) of 15-30 MPa, a modulus of elasticity (ASTM D638) of 300-600 MPa, and an elongation at break (ASTM D638) of 40-150%.

[0014] In specific embodiments, the polymer resin used to fill the one or more through slits in the metal layer comprises an acrylated urethane resin such as those available from Dymax Corporation. Suitable resins particularly include acrylate-terminated urethane oligomer resins available from Dymax Corporation as Light-Weld® 431-BF, Light-Weld® 3013, and Multi-Cure® 921-T. Of course other resins meeting the above-described properties can be used, particularly other UV-curable urethane resins.

[0015] Applicants have surprisingly found that, unlike the epoxy resins used to fill the through slits in the prior art, cured resins meeting the above-described properties will not delaminate from the smartcards even after repeated flexing of the smartcards.

[0016] The resins can be applied and cured in a number of ways. For example, in some embodiments the uncured resin is deposited over the slit(s) so as to substantially cover the slit(s). Thereafter, the uncured resin is forced into the slit by pressure, such as by using a doctor blade (also referred to as a squeegee) or a roller. A doctor blade/squeegee is particularly useful in that it can effectively remove excess resin from the surface of the smartcard (i.e., resin that is not forced into the slit). Once the resin fills or substantially fills the slit(s), the resin is cured using UV light and/or heat. In the case of UV curable resins, the resin material and UV light source can be chosen such that curing is accomplished in less than 20 seconds, less than 10 seconds, or less than 5 seconds.

[0017] In order to ensure adequate adherence of the resin within the slit(s), the metal layer can be subjected to a plasma pretreatment in order to remove any organic materials and other contaminants. Plasma pretreatment can be conducted in a vacuum or at atmospheric pressure (i.e., in air). Various other surface cleaning methods can be used instead of or prior to plasma pretreatment, such as cleaning the surface with a suitable solvent (e.g., by wiping the surface with isopropyl alcohol).

[0018] FIG. 1 depicts one embodiment of a metal layer (or sheet) (10) of the present disclosure having an opening (or recess) (12) in which a transponder chip module (14) is positioned. A slit (16) extends from the opening (12) to an outer edge (18) of the metal layer (10), and is filled with a cured resin according the methods described herein. The metal layer is part of the metallic smartcard (20), which typically includes one or more additional layers, as explained, for example, in U.S. Patent Publication Nos. 2015/0021403 and 2019/0197386 (the “Finn Pubs.”) and 2019/0197384.

[0019] The method of the present disclosure is also suitable for filling slits in the metal layers for multiple smartcards at a time. By way of example, a metal sheet (e.g., stainless steel) sized for a plurality of smartcards (e.g., 25 cards) can be processed so as to form slits in a plurality of predetermined locations. Thereafter, the sheet is placed on a support surface and a plurality of computer-controlled nozzles (e.g., five) traverse above the slits (e.g., by moving the nozzles and/or the support surface) in a predetermined pattern so as to deposit the resin over the slits. Next, a squeegee is wiped, under pressure, across the sheet in order to force the resin into the slits and remove excess resin from the surface. The sheet is then advanced beneath a UV light source (e.g., a UV light tunnel) to cure the resin within the slits. Thereafter, metal layers for individual cards can be cut from the sheet such that one of the slits is provided in each of the metal layers, extending to an outer edge of the metal layer, thereby providing slitted metal layers for multiple smartcards (e.g., 25 cards from one sheet).

[0020] In an alternative embodiment, the resin is applied above the slits from nozzles such that the resin is drawn into the slits by capillary action. Thereafter, the metal sheet is flipped over and advanced beneath a UV light source. After such UV curing, the sheet if flipped back over and uncured resin is wiped from the surface of the metal sheet not exposed to UV light for curing.

[0021] In the embodiments described herein, after the resin within the slits has been cured and uncured resin removed from the metal surface(s), a powder coating can optionally be applied to one or both surface of the metal sheet or layer.

[0022] While various embodiments of a method for filling a through slit in a metallic smartcard have been described in detail above, it will be understood that the components, features and configurations, as well as the methods of manufacturing the devices and methods described herein are not limited to the specific embodiments described herein.