阅读说明：本技术 用于芯片卡的生物识别传感器模块及所述模块的制造方法 (Biometric sensor module for chip cards and method for producing said module ) 是由 克里斯托夫·马蒂厄 卡斯滕·尼兰德 于 2020-04-16 设计创作，主要内容包括：用于芯片卡的生物识别传感器模块(4)的制造方法,包括以下步骤-提供包括正面和背面的介电载体(101),该正面和该背面均形成该载体(101)的主面,-将用于检测指纹的生物识别传感器(300)附连至该背面,在该背面上的由该传感器覆盖的检测区部与在该正面上的检测区域相对放置,-在该载体(101)的被电连接至该生物识别传感器(300)的该背面上制成导电连接片(7),至少一个连接片(7)包括可被焊接材料润湿的区域,该区域在0.2平方毫米和5平方毫米之间的面积上延伸。(Method of manufacturing a biometric sensor module (4) for a chip card, comprising the steps of-providing a dielectric carrier (101) comprising a front face and a rear face, both forming a main face of the carrier (101), -attaching a biometric sensor (300) for detecting a fingerprint to the rear face, a detection zone portion covered by the sensor on the rear face being placed opposite a detection zone on the front face, -making an electrically conductive connection piece (7) on the rear face of the carrier (101) which is electrically connected to the biometric sensor (300), at least one connection piece (7) comprising an area wettable by a soldering material, the area extending over an area between 0.2 and 5 square millimetres.)

1. A biometric sensor module for a chip card, comprising

-a dielectric carrier (101) comprising a front side and a back side, both forming a main side of the carrier (101),

-a biometric sensor (300) for detecting a fingerprint, the biometric sensor being attached to the rear face and extending at a detection zone portion below the rear face, the detection zone portion facing a detection area located on the front face of the carrier (101),

-a conductive connection pad (7), the conductive connection pad (7) being arranged on the back side of the carrier (101) and being electrically connected to the biometric sensor (300),

characterized in that at least one connecting piece (7) comprises an area which can be wetted by the soldering material, said area extending over an area of 0.2 mm and 5 mm.

2. Module according to claim 1, wherein at least one connecting tab (7) has an area wettable by the welding material, said area being delimited by a substantially continuous perimeter adopting a shape selected from the group consisting of rectangular, rhomboidal, square, oblong or circular.

3. Module according to claim 2, wherein at least one connecting tab (7) comprises an extension (10) extending from the area wettable by the solder material towards the free end.

4. Module according to any one of the preceding claims, wherein the mass (6) of welding material is deposited on a wettable zone of at least one connecting tab (7), the mass having a volume of between 0.002 and 0.070 cubic millimetres.

5. The module of claim 4, wherein the solder material is an alloy having a melting point less than or equal to 140 ℃, and the alloy is selected from the group consisting of tin/bismuth, tin/bismuth/silver, and tin/indium.

6. Module according to claim 4 or 5, wherein the mass of welding material (6) has a height, measured perpendicular to the carrier (101), between the surface of the tab (7) on which it is deposited and its highest point, of between 0.040 millimetres and 0.150 millimetres.

7. Module according to any one of the preceding claims, wherein at least one connection pad (7) is placed substantially opposite the area of the front face covered with a frame (5), and at least one conductive via (104) is made in the thickness of the carrier (101), the via (104) electrically connecting the frame (5) to the connection pad (7).

8. Module according to any one of the preceding claims, wherein the dielectric carrier (101) is a flexible carrier from the polyimide series.

9. Chip card comprising a card body with a circuit (200) integrated into the card body and a module (4) according to any one of the preceding claims, the module (4) and the circuit (200) being electrically connected using a soldering material (6).

10. The chip card of claim 9, wherein the module (4) and the circuit (200) are electrically connected using a soldering material (6) deposited on at least one connection pad (7), the melting point of the soldering material being lower than or equal to 140 ℃.

11. The chip card of claim 9 or 10, wherein the module (4) and the circuit (200) are electrically connected using a soldering material (6) deposited on at least one connection pad (7) and a soldering material (206) deposited on the circuit (200), the melting point of the soldering material (6) deposited on at least one connection pad (7) being lower than or equal to the melting point of the soldering material (206) deposited on the circuit (200).

12. Method for producing a biometric sensor module (4) for a chip card, comprising the following steps

-providing a dielectric carrier (101) comprising a front side and a back side, both forming a main side of the carrier (101),

-attaching a biometric sensor (300) for detecting a fingerprint to the rear face, a detection area portion covered by the sensor on the rear face being placed opposite a detection area on the front face of the carrier (101),

-making a conductive connection pad (7) on the back side of the carrier (101), the conductive connection pad (7) being electrically connected to the biometric sensor (300),

characterized in that at least one connecting piece (7) comprises an area which can be wetted by the soldering material and which extends over an area of 0.2 to 5 square millimeters.

13. A method according to claim 12, wherein the mass (6) of soldering material is deposited on the connecting piece (7).

14. Method according to claim 13, wherein the welding material (6) is deposited on the connection piece (7) by spraying.

15. The method according to claim 13 or 14, wherein the soldering material (6) is deposited on a connecting pad (7) after the biometric sensor (300) has been attached to the back side of the carrier (101).

16. The method according to any one of claims 12 to 15, wherein the biometric sensor (300) is attached to the back side of the carrier (101) using an adhesive for attaching a chip and cross-linked at a temperature between 100 ℃ and 150 ℃.

Technical Field

The invention relates to the field of chip cards.

Background

In the field of chip cards, in particular as payment devices, manufacturers always want to provide greater security for the users. It has therefore been proposed to integrate a biometric sensor for reading a fingerprint into a chip card. For examples of such cards, reference may be made, for example, to patent application DE10139414a1 and patent application US20170277936a 1.

For example, for cards that benefit from contact-based and contactless read modes, a module integrated into the card and including a biometric sensor may allow transaction authorization only if the cardholder's fingerprint is detected. This type of card is described, for example, in patent document publication No. EP 3336759 a 1. To manufacture such cards, a cavity is milled into the card in order to expose the circuitry pre-integrated into the card body and to accommodate the module at this cavity. The module received in the cavity is then also electrically connected to the circuit.

Integrating a module comprising a biometric sensor into a card is a difficult operation. In particular, the connection between the module and the circuit of the card must be reliable, stable over time, not cause damage to the sensor, and should not negatively affect the aesthetics of the card, etc.

It is an object of the invention to at least partly contribute to facilitating the integration of a module into a card.

Disclosure of Invention

Thus, according to the invention, a biometric sensor module for a chip card is proposed, comprising

A dielectric carrier comprising a front side and a back side, both the front side and the back side forming main faces of the carrier,

a biometric sensor for detecting a fingerprint, the biometric sensor being attached to the back face and below the back face above a detection zone,

-a conductive connection pad arranged on the back side of the carrier and electrically connected to the biometric sensor.

In this module, at least one connecting piece comprises a region which can be wetted by the solder material, which region extends over an area of between 0.2 and 5 square millimeters and advantageously over an area of equal to or greater than 0.79 square millimeters.

Thus, by virtue of these dimensions of the area of the region wettable by the solder material, the shape of the mass (or bead) of solder material to be deposited on the tab can be controlled. As used herein, the term "glob" is used to refer to the solder material before deposition on the tab and after deposition on the tab (the term "glob" is typically used before deposition on the tab and when the solder material has been deposited on the tab, the term "glob of solder material" is typically used). Generally, herein, the term "glob" refers to the shape of the solder material that is deposited on the tab, but where applicable, those skilled in the art will appreciate that depending on the context in which the term "glob" is used, whether or not the term may refer to solder material that has not yet been deposited on the tab. For example, the mass of solder material may be obtained by depositing the material on a wettable zone and by using a reflow technique or by depositing the mass in liquid form and then cooling it. The controlled shape of the mass of solder material makes it possible to obtain a solder material having a height sufficient to connect the connection pads to the circuit of the card, while avoiding the solder material from creeping tin in an uncontrolled manner, for example during at least partial reflow of the solder material when embedding the module, and in particular between the module and the walls of the cavity onto the surface of the card.

The chip card module optionally comprises one and/or the other of the following features, each considered independently of one another or each considered in combination with one or more other features:

-at least one connecting piece has an area wettable by the welding material, delimited by a substantially continuous perimeter having a shape selected from rectangular, rhomboidal, square, oblong or circular;

-at least one connecting tab comprises an extension extending from an area wettable by the welding material to a free end;

-depositing a mass of welding material on the wettable area of at least one connecting tab, the mass having a volume between 0.002 cubic millimetres and 0.070 cubic millimetres;

the solder material is an alloy with a melting point lower than or equal to 140 ℃, for example included in the list of tin/bismuth, tin/bismuth/silver and tin/indium compositions;

the mass of welding material has a height, measured perpendicularly to the carrier, between the surface of the connecting piece deposited thereon and its highest point, and between its highest points between 0.020 and 0.200 mm, more preferably between 0.040 and 0.150 mm;

-at least one connection pad is placed substantially opposite the front area covered with a frame and at least one conductive via is made in the thickness of the carrier, the via electrically connecting the frame to the connection pad; and

the dielectric support is a flexible support from the system included in the list of polyimide, polyethylene terephthalate (PET and PET copolymers), polyethylene naphthalate and epoxy glass.

According to another aspect, the invention relates to a chip card comprising a biometric sensor module according to the invention. The chip card comprises a card body in which an electric circuit is integrated. The module and the circuit are electrically connected to each other using a solder material.

The chip card optionally comprises one and/or the other of the following features, each considered independently of the others, or each considered in combination with one or more other features:

-the module and the circuit are electrically connected using a soldering material, the soldering material being deposited on at least one connection pad, the melting point of the soldering material being lower than or equal to 140 ℃;

-the module is electrically connected with the circuit using a solder material deposited on at least one tab and a solder material deposited on the circuit, the solder material deposited on at least one tab having a melting point lower than or equal to the solder material deposited on the circuit.

According to another aspect, the invention relates to a method for manufacturing a biometric sensor module for a chip card, comprising the following steps:

-providing a dielectric carrier comprising a front side and a back side, both the front side and the back side forming main faces of the carrier,

attaching a biometric sensor for detecting a fingerprint to the back face, a detection area portion covered by the sensor on the back face being located opposite a detection area on the front face,

-making conductive connection pads on the back side of the carrier that is electrically connected to the biometric sensor.

According to the method, at least one connecting piece comprises an area wettable by the soldering material, which extends over an area equal to or greater than 0.79 square millimeters.

The method optionally includes one and/or the other of the following features, each considered independently of the other or each considered in combination with one or more other features:

-the mass of soldering material is deposited on the connection piece;

-depositing solder material on the connection pads using the techniques included in the list comprising spraying, placing solder material balls (solder balls), dispensing liquid or paste solder material, printing liquid or paste solder material (screen printing), transferring liquid or paste solder material using the tips of the pins (pin transfer), placing using preformed solder material (solder material preform), followed or not by a reflow step;

-the soldering material is deposited on the connection pad after the biometric sensor has been attached to the back side of the carrier; and

-attaching the biometric sensor to the back side of the carrier using an adhesive for attaching a chip and cross-linked at a temperature between 100 ℃ and 150 ℃.

Drawings

Other aspects, objects and advantages of the invention will become apparent from a reading of the following detailed description and a review of the accompanying drawings, given by way of non-limiting example, in which:

FIG. 1 schematically shows a perspective view of a chip card according to a first example of embodiment of the invention;

FIG. 2 schematically shows a perspective view of a chip card according to a second example of embodiment of the invention;

FIG. 3 schematically illustrates cross-sectional views of various steps of one example of a method of manufacturing a biometric sensor module, such as the biometric sensor module integrated into the card shown in FIG. 2;

fig. 4 schematically shows a cross-sectional view of a biometric sensor module integrated into a card obtained using a method such as that shown in fig. 3;

fig. 5 schematically shows various modifications that can be envisaged for the shape of a connection pad placed on the back side of a biometric sensor module obtained using a method such as that shown in fig. 3; and is

Fig. 6 schematically shows other variations that may be envisaged for the shape of the connection pads placed on the back side of the biometric sensor module obtained using the method shown in fig. 3, for example.

Detailed Description

Fig. 1 shows an example of a chip card 1 according to the invention. In this example, the card 1 is a bank card of the ID-1 specification. It should be noted that this is only an example and that the invention can be applied to other types of cards (controlled access cards, identification cards, traffic cards, logical access control cards, etc.). The card 1 has a first module 2 comprising a connector 3 and an electronic chip (below the connector). The connector 3 makes it possible to electrically connect the electronic chip to a card reader in order to exchange data between the chip and the card reader.

In the case of a dual interface card, i.e. allowing contact or contactless reading, the card 1 also has an antenna integrated into the body of the card 1. For example, the antenna is connected to a chip located in the first module 2. The antenna allows contactless data exchange between the chip and the contactless reader. This antenna or another part of the circuit located in the body of the card 1 is also electrically connected to a second module 4 integrated into the card 1. The second module 4 is a biometric module. The biometric module 4 comprises a sensor for fingerprint recognition. The second module 4 makes it possible to determine whether the fingerprint read by the sensor corresponds to the fingerprint of a user authorized to use the card 1. In this case, contactless communication between the chip and the reader may be authorized.

The exemplary embodiment of the card 1 shown in fig. 2 differs from the exemplary embodiment shown in fig. 1 mainly in that the second module 4 comprises a conductive border 5 (border 5) which may be continuous or discontinuous. The bezel 5 is electrically connected to the biometric sensor located on the back of the second module 4. Which allows for the removal of potential static charge that may damage the sensor or prevent the sensor from reading a fingerprint. In fig. 2, the frame 5 has the shape of a continuous ring. According to some variants, the bezel 5 may be composed of a plurality of conductive segments or conductive points arranged around the area on which the finger is to be placed to read the corresponding fingerprint.

A method of manufacturing a module of the type shown in figure 2 is described below.

The process comprises the following steps:

providing a composite material 100, the composite material 100 comprising a carrier 101 made of a dielectric material, a sheet consisting of an electrically conductive material 102 being laminated on the carrier 101 (see fig. 3 a); for example, the dielectric material is a polyimide with a thickness comprised between 25 and 75 microns, and preferably equal to 50 microns, and the first conductive material 102 is a copper alloy with a thickness comprised between 12 and 35 microns, and preferably equal to 18 microns; in order to effectively implement the method according to the invention on an industrial scale, the composite material 100 (copper clad) is advantageously provided in the form of a roll and the method is implemented in a roll-to-roll manner;

coating the face of the dielectric material opposite to the face on which the first conductive material is laminated with an adhesive material 103 (see fig. 3 b); for example, the bonding material 103 is an epoxy resin that may be modified with mineral fillers and resins; thus, the adhesive material 103 is deposited at a thickness between 10 and 25 microns; the adhesive material 103 may undergo a continuous drying process to remove the solvent present in the formulation upon deposition;

making holes 104 through the new composite material comprising the dielectric carrier 101, the first layer of conductive material 102 and the layer of adhesive material 103 (see fig. 3 c);

-laminating a second layer 105 of conductive material; for example, the second conductive material is a copper alloy with a thickness between 12 and 35 microns, and preferably with a thickness equal to 18 microns; the layer of second conductive material 105 closes the hole 104 (see fig. 3 d); the adhesive material 103 may undergo a cross-linking step after a defined cycle of temperature plateau with suitable chemical properties of the adhesive material 103;

laminating a dry photoresist film 106 (see fig. 3e) on each of the two main faces of the composite obtained upon completion of the previous step, respectively, and then exposing and stripping the photoresist through a mask to form a pattern for the subsequent step;

etching specific areas of the first layer of conductive material 102 and the second layer of conductive material 105;

electrolytic deposition of a multilayer metal 107 (for example copper, nickel, gold, palladium or silver), the multilayer metal 107 being intended to facilitate the soldering of the connection line to the second conductive material and/or the making of a conductive via at the hole 104 between the first conductive material 102 and the second conductive material 105;

-depositing a layer of protective material 108 on the detection area; for example, the protective material 108 is a photoimageable cover material, i.e., a photosensitive material; for example, the thickness of the layer of protective material 108 is between 15 microns and 50 microns, for example equal to 25 microns; for example, the protective material layer 108 is deposited as a film laminated on the front side of the carrier 101; for example, the layer of protective material 108 is deposited in the form of an epoxy-acrylate film (e.g., which is a product sold under the reference numeral by ethernet (www.eternal-group.com)); alternatively, the protective material layer 108 is deposited by using a screen printing technique; as another alternative, the layer of protective material 108 is deposited using techniques similar to inkjet techniques; as another alternative, the protective material layer 108 is deposited using a coating technique; the protective layer 108 extends over an area corresponding to the detection area on the front side; and is

In the case of depositing the protective material layer 108 using a non-selective deposition technique, after depositing the protective material layer 108, it may be necessary to perform a step of exposure to suitable radiation through a mask, followed by a chemical treatment step;

-a step of thermally crosslinking the protective layer.

By means of the protective material layer 108 consisting of a photoimageable covering material, the carrier 101 can be protected with a relatively mechanically and chemically resistant material, the use of which can be easily integrated into industrial processes, in particular roll-to-roll processes, compatible with the heating steps required for possible soldered connections of the module 4 to the circuit 200 already integrated in the card body. Its photoimageable properties are also compatible with the implementation of industrially controllable and high-throughput compatible lithographic steps.

Preferably, the protective layer 108 comprising the photoimageable covering material is based on an epoxy-acrylate resin, which, after UV or thermal crosslinking, has physicochemical properties, in particular in terms of hardness and abrasion resistance, superior to those which can be obtained, for example, from pure acrylates. Likewise, epoxy-acrylate resins are easier to implement than epoxy resins.

According to one embodiment of the method according to the invention, the soldering material 6 is deposited in the preceding step on the connection pads 7 made in the first layer of conductive material 102. For example, the solder material 6 is a tin-bismuth alloy, a tin-bismuth-silver alloy, or a tin-indium alloy. For example, the solder material 6 is deposited using screen printing or spraying (or using other methods as described above). Furthermore, instead of using the electrolytically deposited multilayer metal 107 to make the hole 104 electrically conductive, the step of depositing the soldering material 6 may be used to deposit the material in the hole 104 so that the hole 104 is electrically conductive between the first layer of electrically conductive material 102 and the second layer of electrically conductive material 105.

The solder material 6 may be deposited on various shapes of the connecting pieces 7 (see fig. 5). For example, the shapes have a substantially continuous perimeter that defines an area wettable by the weld material in the shape of a rectangle, a diamond (which may be square), an oblong or a circle.

Alternatively, instead of depositing the welding material 6 on the connecting tab 7, the connecting tab 7 is left untreated prior to the operation of embedding the module 4 in the card 1. Then, during the embedding operation, before the module 4 is mounted in the cavity 208 formed in the card body (for example by milling), a soldering material 6, paste or anisotropic conductive film 6' is deposited on the connection pads 7 to establish a connection with the circuit 200 housed in the card body (see fig. 3g and 4). When the paste or the anisotropic conductive film 6 'is used, the connection sheet 7 may take a shape such as those described above with reference to fig. 5, or the connection sheet 7 may take a shape having an extension 10 to give the paste better adhesive property or the anisotropic conductive film 6' on the connection sheet 7 better conductivity.

More advantageously, however, the connecting pads 7 have a shape compatible with both the use of the soldering material 6 and with the paste or anisotropic conductive film 6'. To this end, the connecting tab 7 may take a shape comprising an area wettable by the welding material delimited by a substantially continuous perimeter taking a shape selected from a rectangle, a rhombus, a square, an oblong or a circle, and a lateral extension 10 extending from the area wettable by the welding material towards the free end (see fig. 6).

At the end of the above steps, a roll with a biometric sensor carrier 200 for a chip card is obtained. Each of these carriers 200 has a structure corresponding to the structure shown in, for example, fig. 3f1 or fig. 3f2, respectively, depending on whether the biometric sensor is assembled before the solder paste 6 is deposited on the pads 7 or after the solder paste 6 is deposited on the pads 7. Thus, each carrier 200 comprises:

a front surface having a rim 5 formed in a second layer 105 of conductive material and a protective layer 108 deposited on the layer 103 of adhesive material at a detection area located inside the loop formed by the rim 5;

a back side with tabs 7, possibly with a glob of soldering material 6 deposited on at least some of the tabs 7, in order to be able to subsequently connect the module 4 to the circuit 200 integrated into the card body.

In order to be used and integrated into a chip card, each carrier 200 is equipped with a biometric fingerprint sensor 300. The biometric sensor 300 is secured to the back side using, for example, known die attach techniques. For example, the biometric sensor 300 is fixed to the back of the carrier 101 using a thermosetting adhesive that cures at a temperature between 100 ℃ and 150 ℃ and has the property of migrating under the entire surface of the sensor by capillary action without creating any gaps or air bubbles ("underfilling").

The solder material 6 is deposited on the attachment tab 7 before or after assembly of the biometric sensor 300, but preferably the solder material 6 is deposited on the attachment tab 7 after assembly to avoid the biometric sensor 300 experiencing thermal shock during a reflow operation of the solder paste forming the solder material 6.

Likewise, the solder material 6 is deposited using screen printing or spraying (or using other methods as described above).

If the biometric sensor 300 is already assembled on the dielectric carrier 101, the soldering material 6 is preferably deposited on the connection pads 7 by spraying.

The biometric sensor 300, on its back, occupies an area substantially corresponding to the detection zone located at the detection zone opposite the area where the protective layer 108 is deposited. The biometric sensor 300 is connected to the connecting pads 7 and the bezel 5 using known techniques, such as flip-chip technology or wire bonding technology using wires 11. Advantageously, the biometric sensor 300 and its possible leads 11 are protected in an encapsulating resin 12. It is also possible for the hot-melt adhesive 10 to be arranged on the rear side of the connecting lug 7 or on the rear side next to the connecting lug 7. The hot melt adhesive 10 is intended to fix the biometric sensor module 4 in a cavity 208 formed in the chip card body.

When the module 4 is embedded in the card body, there are several possible options for establishing a connection between the connection pads 7 of the module and the circuit 200 integrated into the card body. For example, bond pad 7 may be soldered directly to circuit 200 (see fig. 4) using solder material 6 deposited on bond pad 7. Alternatively, a bolus 206 of solder material may be deposited on the circuit 200 and a connection formed between the solder tab 7 and the circuit 200 by melting one solder material, another solder material, or both solder materials previously deposited on the tab 7 and on the circuit 200, respectively. More specifically, for example, a first solder material 6 may be deposited on the bond pad 7 and a second solder material 206 may be deposited on the circuit 200. The second soldering material is preferably deposited on the circuit 200 before the final completion of the card body, i.e. before stacking and laminating the various constituent layers of the chip card 1. The first solder material 6 is then advantageously a solder material having a low melting point (e.g. a melting point lower than or equal to 140 ℃) and the second solder material 206 has a higher melting point close to or equal to the melting point of the first solder material 6. Advantageously, the use of the second solder material 206 having a higher melting point may limit the risk of the solder material or materials creeping tin into and towards the edges of the cavity 208, or even out beyond the edges of the cavity 208.

For example, in order to make a connection between the connection pad 7 and the circuit 200, a thermode 400 is placed on the frame 5. Since the frame 5 advantageously faces the connecting webs 7 on both sides of the carrier 101, there is particularly good heat conduction between the two faces of the carrier 101.

On the connection pads 7 a first soldering material 6 with a low melting point (lower than or equal to 140 ℃) and on the circuit 200 a second soldering material 206 with a higher melting point are used, the thermode 400 heated to a temperature of, for example, 230 ℃ being applied for 2.5 seconds. The heat provided by the thermode 400 is also dissipated into the hot-melt adhesive 10, thereby bonding the module 4 into the card 1.

A thermode 400 heated to a temperature of, for example, 230 c is applied for 1.5 seconds using a first solder material 6 having a low melting point (140 c or lower) on the connection pad 7 and a second solder material 206 having a melting point equal to, close to, or lower than the first solder material 6 on the circuit 200. In this case, therefore, the method according to the invention is faster. Furthermore, the use of soldering material 6, 206, with a low melting point, makes it possible to use thermodes 400 with a smaller carrier surface, possibly contributing to a better control of the tin-climbing and limiting the risks of deformation of card 1 and/or module 4.

In general, module 4 may be connected to circuit 200 using a conductive adhesive or paste 6', an anisotropic conductive film, or a solder material 6. In any case, however, the above-described method or variants thereof is advantageously used by making the connecting tabs 7 with a shape compatible with the use of the soldering material 6, the paste or anisotropic conductive film 6', and the radial or lateral extensions 10 (see fig. 6), which may be rectangular, corresponding to a rhombus, square, oval or disc. The module 4 according to the invention is then the same whether connected by soldering or using a conductive adhesive. This makes it possible to manufacture the module 4 on a larger scale, while still allowing the insert to select one connection technique or another.

The manufacture and embedding of the module 4 including the bezel 5 on the front side has been described with reference to fig. 2, 3 and 4. For example, where biometric sensor 300 is not sensitive or very sensitive to electrostatic charge, bezel 5 may be omitted (see FIG. 1). The above method can then be easily simplified. The fabrication of the holes 104 may be omitted. It is also possible to use only one piece of conductive material 102 (thus omitting in particular the steps shown in fig. 3c and 3 d). The conductive material 102 is then placed only on the back side of the carrier 101 to form the connection pads 7. The overcoat layer 108 is made to cover at least the detection region opposite to the detection region of the sensor 300. The protective layer 108, in addition to the function of actually protecting the carrier 101, also indicates the finger placement position for detecting fingerprints. For example, the protective layer 108 may be colored in a different color in order to coordinate it with the color of the card 1.

The protective layer 108 may be composed of or include ink. For example, it is an epoxy-acrylate based ink. For example, it is a product sold under the reference SD2444NB-M by Peters (www.peters.de).