Biometric sensor module for a chip card and method for manufacturing such a module

Abstract

To find a solution for at least partially improving protection of a detection area without, if possible, sacrificing the appearance of the detection area visible on the surface of the card.SOLUTION: A method for manufacturing a biometric sensor module (4) for a chip card, includes steps of: providing a dielectric substrate having a front face and a back face; and attaching a biometric sensor (300) for fingerprint detection to the back face, where a detection area covered by the sensor (300) on the back face is placed opposite a detection area (108) configured such that a finger is placed on it. At least at the surface of the surface of the detection area (108), the dielectric substrate has an exposed homogeneous polymer material.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to the field of chip cards. [Background technology]

[0002] In the field of chip cards, and especially in the field of chip cards used as payment means, manufacturers are always keen to offer users a higher degree of security and / or ease of use. It has therefore been proposed to incorporate biometric sensors for reading fingerprints into chip cards. To detect a fingerprint, such sensors include a detection element, which is generally formed of a set of sensitive elements (e.g. capacitive elements) arranged in rows and columns under a detection area.

[0003] In cards that benefit from contact-based and contactless reading modes, a module integrated into the card and including a biometric sensor may allow for payments that are authorized only if the cardholder's fingerprint is detected. Cards of this kind are described, for example, in the patent document published in EP 3336759 A1. To manufacture such cards, a cavity is milled into the card to expose the electrical circuitry that is pre-integrated in the body of the card and to accommodate a module therein. The module accommodated in this cavity is then also electrically connected to the circuitry.

[0004] It has been observed that the detection area, on which the finger must be placed in order for the fingerprint to be identified, is exposed to a certain number of factors (humidity, sweat, mechanical wear, UV aging, temperature, etc.) that tend to degrade the detection elements and / or wear out faster than normal. It could be considered to cover the surface of the detection area with a protective layer. But then it is necessary to find a material that at the same time makes it possible to increase the resistance to the attacking factors to which the detection area is exposed and does not interfere with the detection of the fingerprint, but is also compatible with all the other steps of manufacturing, processing and embedding the biometric module. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] European Patent Application Publication No. 3336759(A1) Summary of the Invention [Problem to be solved by the invention]

[0006] The invention aims to find a solution for at least partially improving the protection of the detection area, possibly without sacrificing the appearance of the detection area visible on the surface of the card. [Means for solving the problem]

[0007] What is proposed according to the invention is a dielectric substrate having an outer surface and an inner surface, each of which is located on either side of the dielectric substrate and considered to be along its thickness, the inner and outer surfaces of the substrate corresponding to the main surfaces of the substrate; - tracks and connection pads formed in a sheet of conductive material resting on and fixed to the inner surface of the substrate; - a biometric sensor comprising a detection element formed of a sensitive element, said sensor being connected to at least some pads and fixed to an area of ​​an inner surface that does not have any conductive material, said area of ​​the outer surface located opposite the detection element corresponding to a biometric detection area; an encapsulation part, which is deposited on the inner side of the substrate, at least over the sensor; A biometric sensor module for a chip card, comprising:

[0008] Further, in the present module, at least covering the detection area, an outer surface of the substrate is exposed and corresponds to a homogeneous polymeric material having a glass transition temperature greater than or equal to 110 degrees Celsius.

[0009] Indeed, unlike, for example, glass epoxy, the homogeneous polymer material does not contain any fibers that tend to interfere with biometric measurements, whether capacitive, optical, ultrasonic, or thermal biometric measurements. For example, this homogeneous polymer material is polyimide, polyethylene naphthalate (PEN), or polyether ether ketone (PEEK). Furthermore, having a glass transition point higher than 110° Celsius makes it possible to carry out certain soldering and / or connection techniques and materials for electrical connection between the biometric sensor module and the electrical circuitry integrated in the body of the chip card (for example, solder paste, solder, anisotropic conductive film ACF, etc.), as well as certain assembly and / or embedding methods that include steps involving heating. This homogeneous polymer material is preferably translucent and, for example, black in color.

[0010] The homogeneous polymer material is mechanically resistant (e.g. against the wear of a finger repeatedly placed on the detection area). It is also chemically resistant (e.g. against acidic or basic sweat, against solvents such as fuel, ethanol or other solvents mentioned in the ISO10373-1 standard). The homogeneous polymer material has a relative dielectric permittivity, for example of the order of 2 to 4, preferably between 3 and 3.5, at ambient temperature and at 1 kHz. The dielectric substrate may be integrally constructed of one and the same layer of the same homogeneous polymer material. In this case, its thickness is for example between 25 micrometers and 75 micrometers (for example 50 micrometers). This embodiment makes it possible to manufacture, using a single material, the substrate forming the support for the sensor and for the connection of the sensor to the electric circuit placed in the body of the chip card. Alternatively, if the dielectric substrate is constructed of several layers, said homogeneous polymer material that remains exposed at least over the detection area covers the surface of the outer surface corresponding to this detection area. When the dielectric substrate is composed of several layers of homogeneous polymeric material, it is advantageous for the various layers to have the same relative dielectric permittivity or a relative dielectric permittivity that is close and between 2 and 4 at 1 kHz at ambient temperature, preferably between 3 and 3.5 at 1 kHz at ambient temperature.

[0011] The homogeneous polymer material can be bulk-coloured, in particular black, to give the card an aesthetic touch. The homogeneous polymer material layer thus protects the sensitive elements of the detection element without impeding fingerprint acquisition, while at the same time allowing time to provide potential additional aesthetic value. The homogeneous polymer material layer provides these benefits without the need to add another protective layer, for example, to the outer surface of the substrate.

[0012] This chip card module may optionally comprise the following features, each to be considered independent of the other or each to be combined with one or more of the others: - the sensor is fixed to the inner surface of a dielectric substrate using an adhesive layer whose thickness is between 5 micrometers and 35 micrometers, and the module has first connection pads electrically connected to the sensor and arranged under the encapsulation, and second connection pads electrically connected to the first connection pads, these second pads being intended to connect the module to the chip card circuitry and arranged outside the encapsulation, including one and / or another of.

[0013] According to another aspect, the invention relates to a chip card including a biometric sensor module according to the invention. The chip card comprises a card body with an electrical circuit integrated in the card body. The module and the circuit are electrically connected to each other using a solder material disposed on the connection pads.

[0014] According to yet another aspect, the present invention provides a method for producing a method for manufacturing a pharmaceutical composition comprising: - providing a dielectric substrate having an outer surface and an inner surface, each of which may be considered to be located on either side of the dielectric substrate along its thickness, the inner and outer surfaces of the substrate corresponding to major surfaces of the substrate; - forming tracks and connection pads in the sheet of conductive material, either before or after this layer of conductive material is fixed to the inner surface of the substrate; - fixing a biometric sensor with a detection element formed of a sensitive element to an area of ​​the inner surface that does not have any conductive material, the area of ​​the outer surface located opposite the detection element corresponding to the biometric detection area; - connecting a sensor to at least some of the pads; - encapsulating the sensor in an encapsulation portion; The present invention relates to a method for manufacturing a biometric sensor module for a chip card, comprising:

[0015] Furthermore, at least covering the detection area, the outer surface of the substrate corresponds to a homogenous polymeric material which remains exposed.

[0016] Further aspects, objects and advantages of the present invention will become apparent from a reading of the following detailed description, with reference to the accompanying drawings given as non-limiting examples, in which: [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic perspective view of a chip card according to an example embodiment of the present invention; [Figure 2a] 2A-2C are schematic cross-sectional views of steps in an example of a method for manufacturing a biometric sensor module such as that incorporated in the card shown in FIG. 1. [Figure 2b] 2A-2C are schematic cross-sectional views of steps in an example of a method for manufacturing a biometric sensor module such as that incorporated in the card shown in FIG. 1. [Figure 2c] 2A-2C are schematic cross-sectional views of steps in an example of a method for manufacturing a biometric sensor module such as that incorporated in the card shown in FIG. 1. [Figure 2d] 2A-2C are schematic cross-sectional views of steps in an example of a method for manufacturing a biometric sensor module such as that incorporated in the card shown in FIG. 1. [Diagram 3] FIG. 2C is a schematic cross-sectional view of the integration of a biometric sensor module into a card, obtained using a method such as that illustrated by FIGS. 2a to 2d. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] An example of a chip card 1 according to the invention is shown in figure 1. In this example, the card 1 is a bank card of the ID-1 type. This card 1 has a first module 2 which includes a connector 3 and (below the connector) an electronic chip. The connector 3 makes it possible to electrically connect the chip to the card reader in order to exchange data between the electronic chip and the card reader.

[0019] In the case of a dual interface card, i.e. allowing contact-based or contactless reading, the card 1 also has an antenna integrated into the body of the card 1. The antenna is connected, for example, to a chip located in the first module 2. The antenna allows a contactless exchange of data between the chip and a contactless card reader. The antenna, or another part of the electrical 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 includes a sensor for fingerprint authentication. The second module 4 makes it possible to determine whether the fingerprint read by the sensor matches that of a user authorized to use the card 1. In this case, contactless communication between the chip and the reader can be allowed.

[0020] An example of a method for manufacturing a module of the type shown in FIG. 2 is described below.

[0021] The method comprises a step of providing a composite material 100 comprising a substrate 101 made of a dielectric material, on which a sheet made of a conductive material 102 is laminated (see FIG. 2a). For example, the dielectric material is polyimide, the thickness of which is between 25 and 75 micrometers, preferably equal to 50 micrometers, and the first conductive material 102 is made of copper or a copper alloy, the thickness of which is between 12 and 70 micrometers, preferably equal to 18 micrometers, and for an effective implementation of the method according to the invention on an industrial scale, this composite material 100 is advantageously provided in a reel, the method being carried out in a reel-to-reel mode. The composite material 100 may be provided in the form of a coating, for example a copper coating. Alternatively, the composite material may be provided in the form of a multilayer composite 100 (not shown) comprising a dielectric material substrate 101, a sheet of a conductive material 102 and a layer of adhesive (for example an epoxy material) between the dielectric material substrate 101 and the sheet of conductive material 102. The adhesive has a thickness of for example between 10 and 25 micrometers. This multilayer composite 100 undergoes lamination. The adhesive may undergo a successive drying step in order to drive off the solvents present in the formulation when it was deposited. The adhesive layer thus makes it possible to fix the sheet of conductive material 102 to the inner surface of the dielectric material substrate 101. Lamination may be followed by a step of thermal crosslinking of the adhesive.

[0022] The polyimide forming the substrate 101 is, for example, a thermally stable polyimide (such as an aromatic polyimide), for example Kapton® B Black marketed by DuPont™ or Kymide® Black Polyimide Film (KYPI-B) marketed by Kying®.

[0023] This is followed by steps of a photolithography process to form connection pads and tracks 7 (see FIG. 2b) in the sheet of conductive material 102. These steps include, for example, laminating a dry photosensitive resin film onto the free surface of the sheet of conductive material 102, and then exposing this photosensitive resin film to sunlight through a mask, exposing the photosensitive resin and etching it over certain areas of the sheet of conductive material 102 in order to form connection pads, connection tracks or any other pattern 7.

[0024] Alternatively, the connection pads and tracks 7 are formed by cutting or etching (using leadframe techniques) into a sheet of conductive material 102 before laminating them onto the inner surface of the dielectric substrate 101.

[0025] It is advantageously possible to carry out an electrolytic deposition of a metal layer 107 (e.g. copper, nickel, gold, palladium, silver and their alloys) that is intended to make it easier to solder the connection wires 11 to the conductive material 102 (see FIG. 2c). Other possible techniques for connecting the sensors 300 to the connection pads and tracks 7 may also require one or more metallization steps.

[0026] More specifically, the connection pads and tracks 7 are electrically connected to the sensor 300 and form a circuit including first connection pads arranged under the encapsulation 12 and second connection pads electrically connected to the first connection pads, these second pads intended to connect the module 4 to the chip card circuit 200. These second pads are arranged outside the encapsulation 12 (see further below the explanation regarding FIG. 2d). The first and second pads may be connected by conductor tracks in order to establish the necessary electrical continuity between the inside and the outside of the encapsulation 12.

[0027] According to one particular mode of implementation of the method according to the invention, a solder material 6 is deposited on the connection pads 7 produced in the preceding step on the sheet of conductive material 102 (see FIG. 2d). For example, the solder material 6 is a tin-bismuth alloy or a tin-bismuth-silver alloy.

[0028] Alternatively, instead of depositing the solder material 6 on the connection pads 7, these are left untouched until the step of embedding the module 4 in the card 1. Then, during the embedding step, a solder material 6, paste or anisotropic conductive film 6' is deposited on the connection pads 7 in order to establish a connection with the circuit 200 (see FIG. 3) contained in the card body, before placing the module 4 in a cavity 208 that has been formed (for example by milling) in the card body.

[0029] At the end of the above steps, a reel is obtained containing biometric sensor supports for chip cards, each of which has a structure corresponding, for example, to that shown in FIG. 2d. Each support thus comprises: - an outer surface with a detection area 108 located opposite an area on the inner surface on which the sensitive element of the detection element of the biometric sensor rests; an inner surface with connection pads 7, which may be provided with spherical blobs of solder material 6 deposited on at least some of these connection pads 7, so as to be able to subsequently connect the module 4 to a circuit 200 (see FIG. 3) integrated in the card body; Includes.

[0030] For the purpose of being used and integrated into the chip card 1, each support is equipped with a biometric fingerprint sensor 300. Advantageously, the biometric sensor 300 is insensitive or only slightly sensitive to electrostatic charges. The bezel can therefore be omitted. The method described above is then greatly simplified compared to the prior art method, in which the bezel must be manufactured on the outer surface and then electrically connected (for example using vias) to a circuit placed on the inner surface.

[0031] The biometric sensor 300 is fixed to the rear surface, for example using known die attach techniques. For example, the biometric sensor 300 is fixed to the rear surface of the support 101 using a thermosetting adhesive 400 ("underfill") that cures at temperatures between 100°C and 150°C and has the property of moving under the entire surface of the sensor by capillary action without creating gaps or bubbles. For example, the thickness of the thermosetting adhesive 400 under the biometric sensor 300 is between 5 and 35 micrometers. This is an adhesive without any resin, for example with an amine base.

[0032] Solder material 6 is deposited on connection pads 7 before or after biometric sensor 300 is assembled, but preferably after, to avoid said solder material 6 melting during cross-linking of thermosetting adhesive 400, especially if the solder material is a low temperature solder material.

[0033] Solder material 6 is deposited by screen printing or by squirting. If biometric sensor 300 is already assembled on dielectric support 101, solder material 6 is preferably deposited on connection pads 7 by squirting.

[0034] The biometric sensor 300 occupies a surface area essentially corresponding to the detection area on which it is placed, on the rear face, on the inner face of the dielectric substrate 101, opposite the detection area 108. This biometric sensor 300 is connected to the connection pads 7 using known techniques such as wire bonding using conductors 11, as shown in Fig. 2d and Fig. 3. Alternatively, the biometric sensor 300 is connected to the connection pads 7 using flip-chip techniques. The biometric sensor 300 and its possible conductors 11 are advantageously protected in an encapsulation 12, for example consisting of an encapsulating resin. A hot melt adhesive 10 may also be arranged on the rear face on or adjacent to the connection pads 7. This hot melt adhesive 10 is intended to fix the biometric sensor module 4 in a cavity 208 (see Fig. 3) formed in the body of the chip card.

[0035] When the module 4 is embedded in the card body, there are several possible options for establishing the connection between the connection pads 7 of the module 4 and the circuit 200 integrated in the card body. For example, it is possible to solder the connection pads 7 directly to the circuit 200 using the solder material 6 deposited on the connection pads 7. Alternatively, it is possible to form the connection between the solder pads 7 and the circuit 200 by depositing spherical blobs 206 of solder material on the circuit 200 and melting one, the other or both solder materials previously deposited on the connection pads 7 and the circuit 200, respectively. More specifically, for example, it is possible to deposit a first solder material 6 on the connection pads 7 and a second solder material 206 on the circuit 200. The first solder material 6 is then advantageously a solder material with a low melting temperature (for example a melting temperature lower than or equal to 140° C.) and the second solder material 206 advantageously has a melting temperature close to or equal to the melting temperature of the first solder material 6.

[0036] For example, in order to connect the connection pads 7 to the circuit 200 , thermodes 500 are placed on either side of the support 101 facing the connection pads 7 .

[0037] A thermode 500 is used for 1.5 seconds, for example heated to a temperature of 230° C., using a first solder material 6 with a low melting temperature (lower or equal to 140° C.) on the connection pads 7 and a second solder material 206 with a melting temperature equal to, close to or lower than the melting temperature of the first solder material 6. The method according to the invention is therefore faster in this case. Furthermore, using a solder material 6, 206 with a low melting temperature makes it possible to use a thermode 500 with a smaller bearing surface, which may help to better control creep and limit the risk of deformation of the card 1 and / or the module 4. The method using a low-temperature solder 206 is advantageous for card bodies made of PVC, for example, if the lamination temperature of the circuit 200 in the card with that solder 206 does not exceed 130° C.

[0038] A thermode 500 is used for 2.5 seconds, heated to a temperature of, for example, 230° C., using a first solder material 6 with a low melting temperature (lower or equal to 140° C.) on the connection pads 7 and a second solder material 206 with a higher melting temperature on the circuit 200. The heat provided by the thermode 500 is also dissipated into the hot melt adhesive 10 in order to adhesively bond the module 4 into the card 1. This method of using a solder material 206 with a high melting temperature is advantageous for card bodies made of polycarbonate, for example, when the lamination temperature of the circuit 200 in the card with its solder 206 can reach up to 190° C.

[0039] Generally speaking, it is possible to use conductive adhesive or conductive paste 6', anisotropic conductive film or solder material 6 to connect the module 4 to the circuit 200. In any case, however, the method described above or its variants are advantageously used by manufacturing connection pads 7 having a shape compatible with both the use of solder material 6 and the paste or anisotropic conductive film 6', which shape may be rectangular, diamond, square, oval or disk-shaped and may have radial or lateral extensions. The module 4 according to the invention is then the same whether it is connected by soldering or using conductive adhesive. This allows the module 4 to be manufactured in larger runs, while still leaving the embedder the option of choosing one or the other of the connection techniques.

[0040] For aesthetic reasons and / or to indicate the location of the detection area where the finger should be placed to detect its fingerprint, the dielectric substrate 101 is advantageously bulk colored. For example, the dielectric substrate 101 is a polyimide that is colored black using a pigment or dye. [Explanation of symbols]

[0041] 1. Chip Card 2 First module 3 Connector 4. Second module, biometric sensor module, module 6 Anisotropic conductive film, solder material, first solder material 6' Anisotropic conductive film, conductive adhesive, conductive paste 7 Connect pads, tracks, or any other pattern 10. Hot melt adhesives 11 Connecting wire 12 Encapsulation section 100 Composite materials, multilayer composites 101 Substrate, dielectric material substrate, support, dielectric support, dielectric substrate 102 Conductive material, first conductive material 107 Metal layer 108 Detection Area, Biometric Detection Area 200 Chip card circuits, circuits, electrical circuits 206 Spherical lumps of solder material, second solder material, solder material, low temperature solder 208 Cavity 300 Sensor,Biometric Fingerprint Sensor,Biometric Sensor 400 Thermosetting adhesive, adhesive layer 500 Thermode

Claims

1. A biometric sensor module for a chip card (1), comprising: a dielectric substrate (101) having an outer surface and an inner surface, each of which is located on either side of said dielectric substrate (101) and considered to be along its thickness, said inner surface and said outer surface of said dielectric substrate (101) corresponding to its main surfaces; - tracks and connection pads (7) formed in a sheet of conductive material (102) resting on and fixed to said inner surface of said dielectric substrate (101); a biometric sensor (300) with a detection element made of a sensitive element, said sensor (300) being connected to at least some connection pads (7) and fixed to an area of ​​said inner surface that is free of any conductive material, said area of ​​said outer surface placed opposite said detection element corresponding to a biometric detection area (108) with which a finger placed thereon is adapted to establish contact; an encapsulation (12) deposited on the side of said internal surface of said dielectric substrate (101) and at least on said sensor (300); Including, 1. A biometric sensor module, characterized in that the outer surface of the dielectric substrate (101), at least covering the detection area (108), is exposed and corresponds to a homogeneous polymeric material having a glass transition temperature greater than or equal to 110 degrees Celsius.

2. The module of claim 1 , wherein the dielectric substrate (101) is composed of the homogenous polymer material at least covering and leaving exposed the detection area (108).

3. 3. The module according to claim 1 or 2, wherein the homogeneous polymeric material is selected from the following materials: polyimide, polyethylene naphthalate (PEN) and polyether ether ketone (PEEK).

4. 4. The module of claim 1, wherein the homogeneous polymeric material has a thickness between 25 and 75 micrometers, more preferably close to 50 micrometers.

5. The module of claim 1 , wherein the homogeneous polymeric material is bulk colored.

6. 6. The module of claim 1, wherein the sensor (300) is fixed to the inner surface of the dielectric substrate (101) using an adhesive layer (400) whose thickness is between 5 micrometers and 35 micrometers.

7. 7. The module according to claim 1, having first connection pads electrically connected to the sensor (300) and arranged under the encapsulation (12) and second connection pads electrically connected to the first connection pads, said second pads being intended to connect the module (4) to a chip card circuit (200) and arranged outside the encapsulation (12).

8. The module of claim 1 , wherein the exterior surface does not have a bezel surrounding the detection area (108).

9. A chip card comprising a card body with an electrical circuit (200) integrated therein and a module (4) according to any one of claims 1 to 8, wherein the module (4) and the circuit (200) are electrically connected using a solder material (6, 6') deposited on second connection pads.

10. providing a dielectric substrate (101) having an outer surface and an inner surface, each of which is located on either side of said dielectric substrate (101) respectively considered along its thickness, said inner surface and said outer surface of said dielectric substrate (101) corresponding to its main surfaces; - forming tracks and connection pads (7) in a sheet of conductive material (102) before or after said sheet is fixed to said internal surface of said dielectric substrate (101); - fixing a biometric sensor (300) with a detection element made of a sensitive element to an area of ​​said inner surface that is free of any conductive material, the area of ​​said outer surface located opposite said detection element corresponding to a biometric detection area (108) with which a finger placed thereon is configured to establish contact; - connecting said sensor (300) to at least some pads (7); - encapsulating said sensor (300) in an encapsulation (12); Including, - a method for manufacturing a biometric sensor module (4) for a chip card (1), characterized in that the outer surface of the dielectric substrate (101), at least covering the detection area (108), is exposed and corresponds to a homogeneous polymer material having a glass transition temperature higher than or equal to 110 degrees Celsius.

Images