Card body for a chip card and chip card

Description

[0001] The invention relates to a card body for a chip card and to a chip card comprising a card body.

[0002] This study considers card bodies with a metallic core in the form of a metallic core layer or a metallic core element, as well as cards with dual-interface (DI) functionality, where the card body consists partially or completely of metal. The energy coupling of DI systems with a two-coil system (PLC) is achieved through metal structures with a gap, in which the magnetic / electrical flow is redirected in the metal surfaces.

[0003] The chip module is inserted into a cavity or module opening in the card body.

[0004] The way such a card works is by using a chip module that itself contains a coil (coil-on module). This coil couples to the card body, which has a metal core. This coupling only works if the metal card body contains a slot.

[0005] The cavity design is currently chosen to maximize the cavity or module opening due to electromagnetic considerations, thereby increasing the energy input into the chip module. However, this reduces the module's mechanical stability.

[0006] US 2020 / 257953 A1 describes a smart card with at least one contactless interface, for example, a dual-interface transponder chip module comprising a chip, a module antenna for the contactless interface, and contact pads for a contact interface. Metal layers may have openings to accommodate the module and slots or non-conductive strips extending to the openings, thus forming coupling frames. A card body for the smart card may consist of two such metal layers separated by a layer of non-conductive material. A front-side card layer and a back-side card layer may complete the assembly of multiple coupling frames for a smart card. Various slot designs are described and illustrated. The slot may be filled. The slot may be reinforced.

[0007] US 2020 / 364531 A1 describes a transaction card with a metal layer, an opening in the metal layer for a transponder chip, and at least one discontinuity extending from an origin on the card's circumference to an endpoint in the opening. The card exhibits greater bending resistance than a card with a comparable discontinuity where the endpoint and origin are equidistant from a line defined by a first long side of the card's circumference, provided one or more reinforcing features are missing.Reinforcement features include a discontinuity where one of the endpoints or the origin is relatively closer to the first long side of the map perimeter than the other, a plurality of discontinuities where fewer than all extend from the map edge to the aperture, a self-supporting, non-metallic layer arranged on at least one surface of the map, or one or more ceramic reinforcing tabs surrounding the aperture.

[0008] The object of the present invention is therefore to enable a greater energy input into the chip module even with smaller module openings.

[0009] This problem is solved by a card body for a chip card and a chip card comprising a card body. Embodiments and further developments of the invention are specified in the dependent claims.

[0010] A card body according to the invention for a chip card, comprising a module opening for receiving a chip module with a coil, includes a metallic layer with a slot extending from an outer edge of the metallic layer to the module opening, and a plastic layer applied to one side of the metallic layer. The module opening includes a blind hole cut out in the plastic layer and the metallic layer, and an outer region surrounding the blind hole, which is cut out only to a portion of the height of the plastic layer, wherein at least one further slot is provided in the metallic layer in the outer region.

[0011] A key aspect of the present invention is to introduce additional slots or incisions in the outer region of the module opening. These additional slots result in a focusing of the magnetic field lines, a reduction of eddy currents, and improved coupling of the coil windings.

[0012] The metallic layer is present in the outer area, thus suppressing the formation of magnetic flux around the individual turns of the coil and also the coupling between the individual turns. While magnetic coupling between the individual turns occurs in the blind hole area, where no metallic layer is present, thereby increasing the coil's quality factor, this coupling is suppressed in the area of ​​the metal core. Furthermore, the magnetic flux is compressed, and the magnetic flux also generates eddy currents in the metal core. This means that a significant portion of the energy absorbed by the chip card is lost due to these eddy currents.

[0013] The additional slot(s) now allow for a small module opening, ensuring the module is stable within the card body while still achieving a high energy input for such a small opening. The greater the energy input, the better the chip card's performance.

[0014] This has the advantage of increasing mechanical stability while maintaining a high energy input. The additional slot(s) in the corner areas of the module opening effectively enlarge the electrically active area for energy transfer. At the same time, the module opening is not enlarged across its entire surface, thus preserving the mechanical stability of the smaller opening. In summary, the additional slot(s) in the corner areas of the module opening enable the mechanical design of a smaller opening with the electrical energy input of a larger one.

[0015] Since the energy coupling into the metal card is significantly improved according to the invention, the performance of the chip card increases. The additional slots result in a reduction of eddy currents and field optimization of the magnetic field. This enables, firstly, a faster build-up of the magnetic field strength at a coil of the chip module, which allows for a faster start-up of the chip or processor. Secondly, a higher magnetic field strength at a coil of the chip module is possible, which allows for faster operation due to a higher operating frequency of the chip or processor.

[0016] The term "additional slots" serves to conceptually distinguish these additional slots in the outer area of ​​the module opening from the slot in the metal core, which serves to limit eddy currents. These additional slots are described below in the form of corner slots and parallel slots.

[0017] It is provided that at least one corner slot extends from a corner of the blind hole within a slot area of ​​the outer region. These slots extending from the corners enable the field optimization effects described above. One to four corner slots can be provided, with each additional slot extending from a different corner of the module opening into the metallic layer. Even with one slot, the energy input can be increased. With four slots, preferably arranged symmetrically, the energy input can be increased further.

[0018] Furthermore, it can be provided that at least one corner slot extends at an angle of 45° to an edge of the module opening. This angle has been shown to offer good energy input relative to the slot length.

[0019] It can be provided that at least one corner slot has a length of 1 mm to 2 mm. Measurements have shown that good energy input can be achieved with such lengths.

[0020] It is provided that at least one parallel slot extends parallel to a wall of the blind hole within a slot area of ​​the outer region. These slots, running parallel to the circumference or walls of the blind hole or module opening, enable the field optimization effects described above. One to four parallel slots can be provided, with each additional slot extending into the metallic layer at a different wall area of ​​the module opening. Even with one slot, the energy input can be increased. With four slots, preferably arranged symmetrically, the energy input can be increased further.

[0021] It can also be provided that the length of at least one parallel slot corresponds at least to the length of one wall of the blind hole. This relationship between slot length and side length of the blind hole has been shown to provide good energy input.

[0022] It can be provided that the distance between at least one parallel slot and a wall of the blind hole is between 0.8 mm and 1 mm. This distance has been shown to offer good energy input relative to the slot length.

[0023] It can also be provided that a further plastic layer is applied to a second side opposite one of the metallic layers, and that the inner area of ​​the module opening extends into this further plastic layer. Thus, the metallic layer or core is completely perforated in the area of ​​the module opening, which improves the electrical properties, particularly the energy transmission.

[0024] It can be designed so that the slotted area of ​​the outer region and an unslotted area of ​​the outer region are of the same size. This symmetrical arrangement of the two regions has proven effective for good energy input.

[0025] A chip card according to the invention comprises a card body as described above and a chip module with a coil, which is at least partially embedded in the module opening of the card body. The same advantages and modifications apply as described above.

[0026] It can be designed that the chip module has a base body that supports the coil and that the base body rests on the plastic layer in the outer area of ​​the module opening. This easily avoids direct electrical contact between the chip module and the metallic layer. The chip module and the card body communicate with each other solely via the coils.

[0027] It can further be provided that the slotted area of ​​the outer region and an unslotted area of ​​the outer region are of equal size, and that the coil covers one-third of each of the blind hole of the module opening, the slotted area of ​​the outer region, and the unslotted area of ​​the outer region of the module opening. Thus, two-thirds of the coil's windings in the chip module can be used for energy input. Simultaneously, two-thirds of the chip module's contact surface can be used for a mechanical connection. The slotted area is used for two purposes: electrically for energy input and mechanically for stable mounting of the chip module.

[0028] The present invention is described below by way of example with reference to the accompanying drawings. Fig. 1: a sectional view of a chip card with card body and chip module; Fig. 2: a top view of a card body for a chip card; Fig. 3: a bottom view of a chip module; and Fig. 4: a schematic representation of the magnetic flux in an area of ​​the chip module; and Fig. 5: a detail of the module opening of the sectional view of the chip card. Figure 1 .

[0029] Fig. 1 shows a card body 10 for a chip card 20. The chip card 20 here comprises the card body 10 and a chip module 30.

[0030] The card body 10 comprises a metallic layer 11, for example in the form of a core or a layer of a stainless steel alloy with a thickness of 400 µm.

[0031] One main surface of the card body 10 is covered or laminated with a plastic layer 12. A second, opposing main surface of the card body 10 is covered or laminated with a further plastic layer 13. The two plastic layers 12 and 13 can be made of materials such as PET, PC, PVC, or PP and have a thickness of 200 µm. The thickness of the card body 10 should not exceed the maximum thickness of a chip card body according to ISO 7810.

[0032] A module opening 14 is provided in the main surface of the card body 10. The module opening 14 extends through the entire plastic layer 12, the entire metallic layer 11, and part of the plastic layer 13. The module opening 14 is created, for example, by a laser or milling operation.

[0033] The module opening 14 has a blind hole 14a cut into the plastic layer 12 and the metallic layer 11 and an outer area 14b surrounding the blind hole 14a, which is cut into the plastic layer 12 only to a portion of its height.

[0034] The chip module 30 is arranged in the module opening 14 and is, for example, glued in place. The chip module 30 comprises a base body 31, which carries the coil 32. The base body 31 rests on the plastic layer 12 in the outer area 14b of the module opening 14.

[0035] The chip module 30 further comprises a chip 33, which is attached, for example, in a potting compound to an underside of the base body 31. The chip 33 is supplied with energy and / or signals via the coil 32. In this way, an electromagnetic field emanating from the metallic layer 11 can be coupled into the coil 32.

[0036] In Fig. 2A card body 10 is shown in plan view. A slot 15 is provided in the metallic layer 11, extending from an outer edge of the metallic layer 11 to the module opening 14. In the Figure 2 The slot 15 is shown on a left side; it can also be located on a right side of the card body 10. The slot 15 serves to prevent eddy currents.

[0037] The slot 15, for example, has a width between 30 µm and 100 µm, preferably between 50 µm and 80 µm. The slot 15 serves to prevent eddy currents in the vicinity of the module opening 14 and is therefore formed in the metallic layer 11. The slot 15 is usually formed in the metallic layer 11 before it is laminated with the plastic layers 12 and 13. Therefore, it is typical for the slot 15 to extend only in the metallic layer 11 and not in the plastic layers 12 and 13.

[0038] The metallic layer 11 has at least one corner slot 16 extending from a corner region of the blind hole 14a into a slot region 14c of the outer region 14b. In this example, four corner slots 16 are provided, each extending at an angle of 45° to an edge of the module opening 14. Each of the corner slots 16 has a length of 1 mm to 2 mm.

[0039] In the metallic layer 11, at least one parallel slot 17 is provided in a slot region 14c of the outer region 14b, extending parallel to a wall of the blind hole 14a. The length of the parallel slot 17 corresponds at least to the length of a wall of the blind hole 14a. The distance between the parallel slot 17 and a wall of the blind hole 14a is between 0.8 mm and 1 mm. In this example, four parallel slots 17 are provided, each running parallel to one of the four walls of the blind hole 14a.

[0040] The individual parallel slots 17 and corner slots 16 are formed separately from one another, so that they have no connection to each other outside the blind hole 14a. The parallel slots 17 and corner slots 16 can be formed in any combination. Thus, it is possible to have only parallel slots 17, only corner slots 16, or both types of slots. For each of the two slot types, one, two, three, or four slots can be provided in the slot area 14c.

[0041] In this example, the module opening 14 has dimensions of 8 mm by 9 mm and a depth of approximately 250 µm.

[0042] Fig. 3Figure 1 shows a lower view of the chip module 30 with a central contact area 34 for connecting chips (not shown) or an integrated circuit. The windings of the coil 32 surround the contact area 34. In this example, the coil 32 has fifteen windings. The coil 32 serves to transmit signals and / or supply energy to the chip of the chip module.

[0043] Fig. 4 Figure 1 shows a schematic representation of the magnetic flux in an area of ​​the chip module 30. The coil 32 with its individual turns 35 is, for example, arranged on a module tape 36.

[0044] In this example, two turns are located in the module opening 14 and are therefore not affected by the metal covering. For the next three turns, the parallel slots 17 and / or the corner slots 16 minimize eddy current formation. The remaining two turns are completely affected by the damping properties of the metal body or the metallic layer 11.

[0045] Fig. 4 Figure 1 shows the course of the magnetic flux 37 around the individual turns 35 of the coil 32. While magnetic coupling between the individual turns 35 is created in the region of the module opening 14 or the blind hole 14a, thus increasing the quality factor of the coil 32, the coupling is suppressed in the region of the metal body. The formation of the magnetic flux 37 is also compressed, and the magnetic flux 37 also generates eddy currents in the metal body. This means that the absorbed energy is lost through the generated eddy currents.

[0046] The parallel slots 17 and / or the corner slots 16 eliminate or at least reduce the suppressive influence of the metallic layer 11. Here, magnetic coupling occurs between the individual windings 35, thereby increasing the energy input.

[0047] Fig. 5 shows a detail of the module opening 14 of the sectional view of the chip card 20. Figure 1 .

[0048] The module opening 14 is shown in the plastic layer 12, the metallic layer 11 and the plastic layer 13. The module opening 14 has a blind hole 14a and an outer area 14b surrounding the blind hole 14a, which is only partially excavated from the plastic layer 12 to a height of its own.

[0049] In the metallic layer 11, a corner slot 16 is shown, extending from a corner region of the blind hole 14a into a slot region 14c of the outer region 14b. The corner slot 16 extends at an angle of 45° to an edge of the module opening 14 and has a length of 1 mm to 2 mm. A parallel slot, not shown here, also runs through the slot region 14c of the outer region 14b.

[0050] In this example, the slotted area 14c of the outer area 14b and a remaining unslotted area of ​​the outer area 14b are of equal size. The remaining unslotted area of ​​the outer area 14b surrounds the slotted area 14c of the outer area 14b. This arrangement has been shown to represent a good compromise between the mechanical stability and electrical performance of the chip.

[0051] Furthermore, the slotted area 14c of the outer area 14b and the remaining unslotted area of ​​the outer area 14b can be of equal size, and the coil 32 can cover one-third of each of the blind hole 14a of the module opening 14, the slotted area 14c of the outer area 14b, and the remaining unslotted area of ​​the outer area 14b of the module opening 14. This arrangement has also proven to represent a good compromise between the mechanical stability and electrical performance of the chip.

[0052] The performance of the chip, and thus of the chip card, depends on how quickly a minimum amount of magnetic field strength can be built up at the coil 32 and how quickly this increases.

[0053] Once a certain minimum magnetic field strength is reached at coil 32, the energy input is sufficient for the chip to operate. This minimum value could be, for example, 1.5 amperes per meter (A / m). The faster this minimum value is reached, the sooner the chip card is ready for use. The corner slots 16 and the parallel slots 17 facilitate the propagation of the electromagnetic field to coil 32, so that the minimum magnetic field strength at coil 32 can be reached quickly. At the same time, the corner slots 16 and the parallel slots 17 reduce the formation of eddy currents, which further improves the energy input into the chip card.

[0054] The increase in magnetic field strength at coil 32 determines when the chip reaches its maximum performance. Typically, there is a saturation region in which the chip's performance does not increase further despite rising magnetic field strength. The chip's performance can be specified, for example, in computational operations per unit of time, such as one second. Here, too, the corner slots 16 and the parallel slots 17 promote the increase in the electromagnetic field at coil 32, as they enable better and faster propagation of the electromagnetic field and thus of the magnetic field strength at coil 32.

[0055] Overall, the corner slots 16 and the parallel slots 17 and the associated smaller module opening 14 achieve a better energy input or better energy coupling than a larger module opening with the total extent of the smaller module opening 14 plus the corner slots 16 and the parallel slots 17.

[0056] Thus, by means of the smaller module opening 14 with the corner slots 16 and the parallel slots 17, increased chip performance can be achieved while simultaneously increasing mechanical stability.

Claims

1. Card body (10) for a chip card (20), comprising a module opening (14) for accommodating a chip module (30) with a coil (32), having a metallic layer (11) with a slot (15) which extends from an outer edge of the metallic layer (11) to the module opening (14), and having a plastics layer (12) which is applied on one side of the metallic layer (11), wherein the module opening (14) comprises a blind hole (14a) made in the plastics layer (12) and in the metallic layer (11), and an external region (14b) which surrounds the blind hole (14a) and which is made in the plastics layer (12) only to the extent of a part of the height of said plastics layer (12), characterized in that in the metallic layer (11) in the external region (14b) there is at least one further slot (16, 17), where at least one corner slot (16) extends in a slot region (14c) of the external region (14b), starting from a corner region of the blind hole (14a), and at least one parallel slot (17) in a slot region (14c) of the external region (14b) extends parallel to a wall of the blind hole (14a).

2. Card body (10) according to Claim 1, characterized in that the at least one corner slot (16) extends at an angle of 45° to a border of the module opening (14).

3. Card body (10) according to Claim 1 or 2, characterized in that the at least one corner slot (16) has a length of 1 mm to 2 mm.

4. Card body (10) according to any of Claims 1 to 3, characterized in that a length of the at least one parallel slot (17) corresponds at least to the length of a wall of the blind hole (14a).

5. Card body (10) according to any of Claims 1 to 4, characterized in that a distance of the at least one parallel slot (17) to a wall of the blind hole (14a) is between 0.8 mm and 1 mm.

6. Card body (10) according to any of the preceding claims, characterized in that a further plastics layer (13) is applied on a second side of the metallic layer (11), opposite the one side, and in that the blind hole (14a) of the module opening (14) extends into the further plastics layer (13).

7. Card body (10) according to any of the preceding claims, characterized in that the slot region (14c) of the external region (14b) and an unslotted region of the external region (14b) are the same size.

8. Chip card (20) comprising a card body (10) according to any of Claims 1 to 7 and a chip module (30), embedded at least partly into the module opening (14) of the card body (10), with a coil (32).

9. Chip card (20) according to Claim 8, characterized in that the chip module (30) has a base element (31) carrying the coil (32) and in that the base element (31) lies on the plastics layer (12) in the external region (14b) of the module opening (14).

10. Chip card (20) according to Claim 8 or 9, characterized in that the slot region (14c) of the external region (14b) and an unslotted region of the external region (14b) are the same size and in that the coil (32) covers a third of each of the blind hole (14a) of the module opening (14), the slot region (14c) of the external region (14b), and the unslotted region of the external region (14b) of the module opening (14).