Circuit for a smart card chip module, smart card chip module and method of manufacturing a smart card chip module

Abstract

Circuit for a smart card chip module (2) comprising an insulating layer having a front main face and a back main face (7). An antenna (8) is made in a first conductive layer located on the back main face (7). The antenna (8) extends over an antenna area set by a periphery (10). The antenna (8) comprises at least one inner winding and at least one outer winding. The outer winding is arranged along the periphery (10) except above at least one first connection segment (16) which turns off or in a central strip (15) of the antenna area towards the center of the antenna area. Furthermore, the outer winding of the antenna comprises at least one second connection segment (18) which turns off from the periphery (10) towards the central strip of the antenna area.

Description

Technical Field

[0001] This invention relates to the field of smart cards, and more particularly to the field of electronic modules for smart cards. Background Technology

[0002] Smart cards have multiple uses: credit cards, SIM cards for mobile phones, transportation cards, identity cards, etc.

[0003] Smart cards typically include a rigid carrier or rigid support made of, for example, plastic, which forms the body of the card. A separately manufactured electronic module, also known as a chip module, is housed within the card's cavity. This chip module includes, for example, a flexible circuit with an electronic chip (integrated circuit) and means for connecting the chip to a device for reading and / or writing data recorded in the chip.

[0004] This invention specifically relates to the field of so-called "dual" cards, which are cards with dual connectivity interfaces to a chip. In other words, these cards allow connectivity with or without contacts. They are also known as "combi" cards.

[0005] In "contact-based" applications, the contacts are connected to the chip and located on one side of the module, thus being flush with the card surface, and allowing electrical connection to the device when the card is inserted into the read and / or write device.

[0006] There are two types of dual-SIM cards for "contactless" applications.

[0007] According to the first type of card, an antenna placed (i.e., integrated, embedded, etc.) in the card body is electrically connected to the chip. In this case, the chip and the reader / writer can exchange data by establishing a direct electrical connection between the reader / writer and the module contacts, or by establishing a direct electromagnetic connection between the antenna and the reader / writer (using, for example, near field communication - NFC technology).

[0008] According to the second type of card, a first antenna, referred to as the "module antenna," is integrated into the module and, through inductive coupling (and therefore no electrical connection), allows electromagnetic coupling to a second antenna, referred to as the "gain antenna or main antenna," embedded in the rigid card body. The first antenna is smaller than the second antenna. Compared to the module, the second antenna can cover a larger area of ​​the card body. This provides a longer range of communication distances. Similarly, in this case, data exchange between the chip and the read / write device can be achieved by establishing a direct electrical connection between the read / write device and the module contacts, either by establishing an electromagnetic connection between the module antenna and the gain antenna, or by establishing an electromagnetic connection between the gain antenna and the read / write device. Thus, the module antenna is connected to the contactless read and / or write device via the gain antenna (through a resonant effect). Therefore, in this second type of dual-card, the only physical connections are at the module level, between the chip and the contacts and between the chip and the module antenna. All these connections are fabricated on the module. This avoids the need for a physical interconnection between the antenna integrated into the card body and the chip integrated into the module.

[0009] For example, international patent application WO2014016332A1 describes a module including a flexible circuit comprising an insulating layer having a front side supporting contacts and a back side supporting a chip and a module antenna. Holes (also called "vias") penetrating the insulating layer can then be fabricated, the inner surfaces of which are metallized to electrically connect the front and back sides of the module. The chip is connected to the contacts and the module antenna using wire bonding or flip-chip technology.

[0010] To facilitate module integration into the card, the antenna must be contained within a module sized according to the ISO 7816-2 standard. Within these dimensions, the back of the module must provide: an area for chip placement, an area for vias, and an area with bonding pads for connecting the chip to contacts and the antenna. Furthermore, the antenna windings must be manufactured in sufficient numbers, with a defined width and minimum spacing between windings to achieve the desired electromagnetic characteristics and resonant frequency. For example, more turns result in higher inductance.

[0011] This invention aims to provide greater flexibility to adapt antenna characteristics to chip specifications. This invention can also be intended to provide modular antennas with high inductance. Summary of the Invention

[0012] A circuit solution is disclosed. Specifically, a circuit for a smart card chip module is disclosed, including an insulating layer having a front main surface and a back main surface. An antenna is disposed in a conductive layer on the back main surface, the antenna extending over an antenna region defined by a periphery having an overall rectangular shape. The antenna includes at least one inner winding and at least one outer winding. The outer winding is arranged along the periphery except above at least one first connecting segment and at least one second connecting segment. Both the first and second connecting segments turn from the periphery toward the central band of the antenna region, or within the central band of the antenna region. Each of the first and second connecting segments is directly electrically connected to a connecting piece. Each of the first and second connecting segments is located on one side of a plane perpendicular to the antenna region. The plane passes through the center of the antenna region and through the middle of two opposite sides of the rectangular shape, and the antenna is substantially symmetrical about the plane.

[0013] In practice, diverting at least two segments from the periphery provides a longer antenna.

[0014] The disclosed circuit may optionally include one or more additional features.

[0015] This disclosure also relates to chip modules and methods for manufacturing chip modules.

[0016] Specifically, the chip module for smart cards disclosed herein includes the circuit and chip as described above, the chip being connected to a connecting piece and another connecting piece, the connecting piece being directly connected to one of the first connecting segment and the second connecting segment, and the other connecting piece being directly connected to the inner turn winding.

[0017] The method for manufacturing the chip module disclosed herein includes:

[0018] - An insulating layer having a front main surface and a back main surface is provided. An antenna is disposed in a conductive layer laid on the back main surface. The antenna extends in an antenna region defined by a periphery, the periphery having an overall rectangular shape. The antenna includes at least one inner turn winding and at least one outer turn winding. The outer turn winding is arranged along the periphery except above at least one first connecting segment and at least one second connecting segment. Both the first connecting segment and the second connecting segment turn from the periphery toward the central band of the antenna region or are located within the central band of the antenna region.

[0019] The first connecting segment and the second connecting segment are each directly electrically connected to the connecting piece. The first connecting segment and the second connecting segment are each located on one side of a plane perpendicular to the antenna region. This plane passes through the center of the antenna region and through the midpoint of two opposite sides of the rectangular shape. The antenna is substantially symmetrical about this plane.

[0020] - Connect the chip to the antenna, wherein, depending on the chip's specifications, the chip is connected to a connecting piece that is directly connected to the first connecting segment, or to another connecting piece that is directly connected to the second connecting segment. Attached Figure Description

[0021] Other features, objects, and advantages of the invention will become apparent from the following detailed description and accompanying drawings, which are given as non-limiting examples, wherein:

[0022] Figure 1 An example of a smart card containing a chip module is shown schematically in perspective view;

[0023] Figure 2 For example Figure 1 The front view of the chip module example of the smart card shown;

[0024] Figure 3 for Figure 2 The rear view of the chip module example shown;

[0025] Figure 4 This is a schematic diagram of various schemes for connecting chips;

[0026] Figure 5 for Figure 2 A front view of a variant of the chip module example shown. Detailed Implementation

[0027] The following describes an example of a circuit embodiment.

[0028] Figure 1 This illustrates a contact and contactless smart card 1, including module 2. Specifically, module 2 includes circuitry 3 and a chip 100 (in... Figure 1 (Not visible in the image). Module 2 is manufactured as a separate component, which is inserted into a recess milled into the body of card 1. The gain antenna (not shown) is integrated into the body of card 1 in a known manner.

[0029] Figure 2 The front side 6 (i.e., the contact surface) of circuit 3 is shown. Figure 3 The back side 7 (bonding surface) of circuit 3 is shown. Figure 2 , Figure 3 and Figure 4The circuit 3 shown is a double-sided printed circuit board with contacts 5 on the front side 6 and an antenna 8 on the back side 7. The contacts 5 are formed in a first conductive layer (e.g., copper, copper alloy, aluminum, aluminum alloy layer) on the front side 6, which is covered by an insulating layer (e.g., epoxy glass, paper, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polyimide). The antenna 8 and connecting piece 9 are formed in a second conductive layer (e.g., copper, copper alloy, aluminum, aluminum alloy layer) on the back side 7, which is covered by the insulating layer. The first and / or second conductive layers may be plated with at least one of the following metals: nickel, gold, palladium, or silver.

[0030] In fact, only a portion of circuit 3 is shown in the figure. This portion essentially corresponds to the part of circuit 3 required for manufacturing module 2. Several similar portions may be supported by the same flexible substrate, such as a flexible substrate used for continuous (i.e., "reel-to-reel" or "roll-to-roll") implementation of the process according to the invention. Module 2 is disposed on circuit 3 by periphery 10. Periphery 10 of circuit 3 corresponding to the portion of module 2 has a rectangular shape with rounded corners between two adjacent sides 11, 12. Periphery 10 includes two short sides 11 corresponding to the two shortest sides of the rectangular shape, and two long sides 12 corresponding to the two longest sides of the rectangular shape.

[0031] Circuit 3 has several contacts 5, to which chip 100 will be connected (see...). Figure 4 For example, each module 2 of circuit 3 includes six contacts 5. One of these contacts is L-shaped and extends between two rows of other contacts 5.

[0032] For example, antenna 8 has approximately ten to thirteen turns of winding. The winding has a width of, for example, 40 micrometers to 100 micrometers. The gap between the windings is, for example, 25 micrometers to 100 micrometers wide. Antenna 8 extends between a starting connector 13 and a ending connector 14. The ending connector is directly connected to the inner turns of antenna 8 ("directly" means there is no antenna or any other connection between the antenna trace and the ending connector 14, i.e., one side of connector 14 corresponds to the antenna trace). The starting connector 13 is positioned near or within the center band of antenna 8, to which chip 100 will be attached. In this document, the center band 15 is defined as the area of ​​module 2, which is defined by the portion of the inner turns of the antenna excluding its U-shaped inner portion (see...). Figure 3(The dashed line in the diagram). The starting connector 13 is close enough to the center of the module to shorten the length of the wire that electrically connects the chip 100 to the antenna 8. From the starting connector 13, the antenna 8 forms a first connecting segment 16 that extends substantially perpendicular to the longest side 12. In the center strip 15, the first connecting segment 16 turns the outer winding of the antenna 8 away from one of the longest sides 12.

[0033] Antenna 8 also has an intermediate connecting piece 17, which is substantially symmetrical to the starting connecting piece 13 about the center line ML1, which connects the two shortest sides 11 and spans between the middle of the two shortest sides 11. The center line ML1 also corresponds to the intersection between the plane in which the antenna is located and the plane perpendicular to the latter ("the latter" corresponds to the antenna plane).

[0034] Intermediate connecting piece 17 is located in the center band 15 of antenna 8. Intermediate connecting piece 17 is close enough to the center point of module 2 to shorten the length of the wire that electrically connects chip 100 to antenna 8. Antenna 8 forms two second connecting segments 18 extending substantially perpendicular to the longest side 12, starting from intermediate connecting piece 17. The second connecting segments 18 turn the outer turns of antenna 8 from one of the longest sides 12 in the center band 15. First connecting segment 16 and second connecting segment 18 extend parallel to each other. The first connecting segment and the second connecting segment are each directly electrically connected to connecting piece 13 and connecting piece 17, respectively ("directly" means that there is no antenna or any other connection between the antenna trace and connecting piece 13 or connecting piece 17, i.e., one side of connecting piece 13 or connecting piece 17 corresponds to the antenna trace).

[0035] Antenna 8 includes a winding having straight portions substantially parallel to the sides 11, 12 of the perimeter 10, curved portions at the corners of the perimeter 10, and a U-shaped inner portion substantially in the middle of the longest side 12. These U-shaped inner portions bypass the starting connecting piece 13 and the intermediate connecting piece 17. The U-shaped inner portions extend on the back surface 7 above a region covered by L-shaped contacts on the front surface 6 (see [link]). Figure 4The overall shape of the windings is symmetrical about the center line ML1 and about the center line ML2. Center line ML1 connects the two shortest sides 11 and spans between the midpoints of the two shortest sides 11, and center line ML2 connects the longest side 12 and spans between the midpoints of the two longest sides 12. The inner connecting piece 19 is directly electrically connected to the inner winding of the antenna and does not necessarily follow the same symmetry ("directly" means there is no antenna or any other connection between the antenna trace and the connecting piece 19 under consideration, i.e., one side of the connecting piece 19 under consideration corresponds to the antenna trace). Their respective positions are fairly symmetrical about the center of module 2. The center of the module corresponds to the intersection of center lines ML1 and ML2, which connect the two shortest sides 11 and the two longest sides 12, respectively, and span between the midpoints of the two shortest sides 11 and the two longest sides 12, respectively.

[0036] The symmetry of antenna 8 improves the surface current and the magnetic field detected or generated by antenna 8.

[0037] The antenna winding forms two support regions, on which the chip 100 can be placed across the two support regions located between the connecting section 16 and the connecting section 18. Specifically, the U-shaped inner portion extends within the central region 15 and forms a coplanar structure of at least 1.5 × 1.5 square millimeters, on which the chip can be attached. This coplanar structure avoids problems that may be related to the tilting of the chip 100.

[0038] Holes 20 penetrating the insulating layer are formed on both sides of the area covered by the longest branch of the L-shaped contact on the front side 6. Each of these holes 20 has an internal cylindrical wall that can be plated with a conductive material (although this is not necessary in this invention). The bottom of each hole 20 is also closed by the first conductive layer. These holes 20 are used to connect the chip 100 to the contact 5. These holes can be manufactured without conductive rings. A method for manufacturing bonding holes without conductive rings can be referred to, for example, patent document FR3006551B1. The absence of conductive rings allows more space to increase the number of antenna winding turns and / or the number of inner connecting pieces 19. It also provides greater flexibility in positioning the inner connecting pieces 19. It also reduces surface currents that circulate in the rings and can interfere with the magnetic field detected or generated by the antenna 8.

[0039] like Figure 4 As shown, the antenna setup described above allows for multiple connection paths (of course, Figure 4All connections shown between chip 100 and connectors 13, 14, 17, and 19 are not necessarily manufactured for an actual product. Chip 100 is connected to the antenna only via two connectors. One of the chip's antenna bonding tabs may be connected to either the starting connector 13 or the intermediate connector 17, while the other antenna bonding tab may be connected to either the ending connector 14 or one or the other of the inner connectors 19 (see example). Figure 4 (Paths A and B in the diagram). These different connection paths connect the chip to antennas of different lengths. Therefore, this not only allows for adaptation to chip characteristics, such as chip inductance, but also allows for adaptation to different locations of the antenna bonding pads on the chip, varying from one commercial chip to another. Specifically, the connection of chip 100 between the initial bonding pad 13 and the intermediate bonding pad 17 allows for the use of shorter wires. In other words, depending on the chip specifications, different bonding pads can be used to connect chip 100 to antenna 8. For example, chip 100 has a bonding pad that is either connected to a bonding pad directly connected to the first bonding segment 16, or connected to another bonding pad directly connected to the second bonding segment 18. Similarly, depending on the chip specifications, chip 100 can also be connected to bonding pads 14, 19 directly connected to the inner turn winding, or connected to another bonding pad directly connected to the inner turn winding.

[0040] Because there is no conductive ring around the hole, the wire can be reduced in size without the risk of short circuits. This also allows for increased speed in the wire bonding process.

[0041] As a variant of the circuit 3 described above, the L-shaped contact has a feature that corresponds to the identifier 21 (see...). Figure 5 One or more cuts. The cuts may allow for an increase in inductance of, for example, 0.3 or 0.4 microhenries.

Claims

1. A circuit for a smart card chip module (2), comprising an insulating layer having a front main surface (6) and a back main surface (7), wherein an antenna (8) is disposed in a conductive layer disposed on the back main surface (7), the antenna (8) extending over an antenna region defined by a periphery (10) having an overall rectangular shape, the antenna (8) comprising at least one inner winding and at least one outer winding, the outer winding being disposed along the periphery (10) except above at least one first connecting segment (16) and at least one second connecting segment (18), both the first connecting segment (16) and the second connecting segment (18) turning from the periphery (10) toward the central band (15) of the antenna region, or within the central band (15) of the antenna region. The first connecting segment and the second connecting segment are each directly electrically connected to a connecting piece (13, 17). The first connecting segment (16) and the second connecting segment (18) are each located on one side of a plane perpendicular to the antenna region. The plane passes through the center of the antenna region and through the middle of the two opposite sides (11) of the rectangular shape. The antenna (8) is substantially symmetrical about the plane.

2. The circuit according to claim 1, wherein the inner turn winding comprises two internal portions, each of the two internal portions extending in the center band (15) of the antenna region and passing between the first connecting segment (16) and the second connecting segment (18), respectively.

3. The circuit according to claim 1, wherein the first connecting segment (16) and the second connecting segment (18) each turn from a point in the middle of one of the other two opposite sides (12) of the rectangular shape of the periphery (10).

4. The circuit according to claim 1, comprising a contact piece (5) disposed in another conductive layer on the main surface (6), at least one of the contact pieces (5) having at least one cutout opposite to the antenna region.

5. The circuit according to claim 1, comprising contact pieces (5) disposed in another conductive layer laid on the main surface (6), at least one of the contact pieces (5) being connected to a bonding hole (20) passing through the insulating layer.

6. The circuit according to claim 5, wherein the bonding hole (20) has no conductive ring surrounding the bonding hole on the back main surface (7).

7. The circuit according to claim 1, wherein the winding of the antenna forms at least two support regions, and the chip (100) can be placed across the at least two support regions, the two support regions being located between the first connecting segment (16) and the second connecting segment (18).

8. A chip module for a smart card, comprising the circuit (3) and chip (100) according to claim 1, wherein the chip (100) is connected to a connecting piece (13, 17) and another connecting piece (14, 19), the connecting piece (13, 17) being directly connected to one of the first connecting segment (16) and the second connecting segment (18), and the other connecting piece (14, 19) being directly connected to the inner winding.

9. A method for manufacturing a chip module, comprising: - An insulating layer having a front main surface (6) and a back main surface (7) is provided. An antenna (8) is disposed in a conductive layer laid on the back main surface (7). The antenna (8) extends in an antenna region defined by a periphery (10), the periphery having an overall rectangular shape. The antenna (8) includes at least one inner winding and at least one outer winding. The outer winding is arranged along the periphery (10) except above at least one first connecting segment (16) and at least one second connecting segment (18). Both the first connecting segment (16) and the second connecting segment (18) turn from the periphery (10) toward the central band (15) of the antenna region or are located within the central band (15) of the antenna region. The first connecting segment and the second connecting segment are each directly electrically connected to the connecting piece. The first connecting segment (16) and the second connecting segment (18) are each located on one side of a plane perpendicular to the antenna region. The plane passes through the center of the antenna region and through the middle of the two opposite sides of the rectangular shape. The antenna (8) is substantially symmetrical about the plane. The manufacturing method further includes connecting the chip (100) to the antenna (8), and wherein, Depending on the specifications of the chip, the chip (100) is connected to a connecting piece that is directly connected to the first connecting segment (16), or to another connecting piece that is directly connected to the second connecting segment (18).

10. The manufacturing method according to claim 9, wherein, Depending on the chip's specifications, the chip (100) is connected to a connecting piece (14, 19) that is directly connected to the inner winding, or to another connecting piece that is directly connected to the inner winding, with two different antenna lengths set between the connecting piece directly connected to the inner winding and the other connecting piece.

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