Biometric sensor module for a chip card and method of manufacturing the module

Abstract

The present application relates to a biometric sensor module for a chip card and a method of manufacturing the module. The method of manufacturing a biometric sensor module (4) for a chip card comprises the steps of providing a dielectric substrate having a front side and a back side; and attaching a biometric sensor (300) for fingerprint detection to the back side of the dielectric substrate, a detection area covered by the sensor (300) on the back side being placed opposite a detection area (108) which is arranged such that a finger can be placed thereon. At least in the surface area of this detection area (108), the dielectric substrate has a homogenous polymer material exposed to the outside.

Description

Technical Field

[0001] This invention relates to the field of chip cards. Background Technology

[0002] In the field of chip cards, and especially in the area of ​​chip cards used as a means of payment, manufacturers have always sought to provide users with better security and / or ease of use. Therefore, the integration of biometric sensors for reading fingerprints into chip cards has been proposed. To detect fingerprints, such sensors include a detection element composed of a set of sensitive elements (e.g., capacitive elements), typically arranged in rows and columns below the detection area.

[0003] For cards that benefit from contact-based and contactless reading modes, a module integrated into the card and including a biometric sensor can authorize a transaction only if the cardholder's fingerprint is detected. This type of card is described, for example, in patent publication EP3336759A1. To manufacture such a card, a cavity is milled into the card to expose circuitry pre-integrated into the card body, and a module is installed within the card body. The module, then installed within the cavity, is subsequently electrically connected to the circuitry.

[0004] It has been observed that the detection area on which a finger must rest to identify a fingerprint is affected by several factors (humidity, sweat, mechanical abrasion, UV aging, temperature, etc.), which can easily lead to degradation and / or premature wear of the detection element. Covering the surface of the detection area with a protective layer could be considered. However, a material must then be found that can significantly increase resistance to the aggressive factors affecting the detection area without interfering with fingerprint detection, and is also compatible with all other steps in the manufacturing, processing, and embedding of the biometric module.

[0005] The object of the present invention is to find a solution that at least partially improves the protection of the detection area, and, if possible, improves the protection of the detection area without sacrificing the appearance of the detection area visible on the card surface. Summary of the Invention

[0006] Therefore, according to the present invention, a biometric identification sensor module for a chip card is provided, comprising:

[0007] - A dielectric substrate having an outer side and an inner side, wherein the outer side and the inner side are each located on one side of the dielectric substrate along the thickness of the dielectric substrate, and the inner side and the outer side of the substrate correspond to the main surface of the substrate.

[0008] - Traces and bonding pads formed in a conductive material foil layer, wherein the conductive material foil layer is located on the inner side of the substrate and is fixed to the inner side of the substrate;

[0009] - A biometric sensor having a detection element formed of a sensitive element, the sensor being connected to at least a number of solder pads, and the sensor being fixed to an area on the inner side of which there is no conductive material, the area on the outer side opposite the detection element corresponding to the biometric detection area; and

[0010] - Encapsulation, which is deposited on the sensor at least on the side where the inner surface of the substrate is located.

[0011] Furthermore, in this module, the outer surface of the substrate includes a homogeneous polymer material in at least the detection area, which is exposed and has a glass transition temperature greater than or equal to 110 degrees Celsius.

[0012] In practice, unlike glass epoxy resins, homogeneous polymer materials do not contain any fibers that could easily interfere with biometric measurements, whether the biometric measurement is capacitive, optical, ultrasonic, or thermal. For example, the homogeneous polymer material is polyimide, polyethylene naphthalate (PEN), or polyetheretherketone (PEEK). Furthermore, a glass transition temperature above 110 degrees Celsius makes it feasible to implement certain soldering and / or bonding techniques and materials (e.g., solder paste, solder, anisotropic conductive film ACF, etc.) for electrical connections between the biometric sensor module and the circuitry integrated into the chip card body, and makes it feasible to implement certain assembly and / or embedding methods that include heating steps. The homogeneous polymer material is preferably opaque and, for example, black.

[0013] The homogeneous polymer material exhibits mechanical resistance (e.g., resistance to abrasion from fingers repeatedly placed on the detection area). It also possesses chemical resistance (e.g., resistance to acidic or alkaline sweat, and also resistance to solvents such as fuels, ethanol, or other solvents mentioned in ISO 10373-1). The homogeneous polymer material has a relative permittivity at ambient temperature and 1 kHz, for example, a relative permittivity of about 2 to 4, and preferably between 3 and 3.5. The dielectric substrate can be integrally constructed from the same layer of the same homogeneous polymer material. In this case, the thickness of the dielectric substrate is, for example, between 25 micrometers and 75 micrometers (e.g., 50 micrometers). This embodiment makes it feasible to use a single material to protect the sensitive element of the sensor and to manufacture a substrate forming a support, wherein the substrate serves to form a support for the sensor and a support for the connection between the sensor and circuitry located in the chip card body. Alternatively, if the dielectric substrate consists of multiple layers, the homogeneous polymer material exposed at least above the detection area covers the outer surface corresponding to the detection area. When the dielectric substrate is composed of multiple homogeneous polymer materials, these different layers advantageously have the same relative permittivity, or have similar relative permittivity between 2 and 4, and preferably have the same or similar relative permittivity between 3 and 3.5 at ambient temperature and 1 kHz.

[0014] Homogeneous polymer materials can be uniformly colored, particularly black, to give cards an aesthetic appeal. Therefore, a homogeneous polymer layer protects the sensitive elements of the detection device without interfering with fingerprint acquisition, while simultaneously enabling the provision of potential additional aesthetic value. The homogeneous polymer layer offers these advantages without the need for, for example, adding another protective layer to the outer surface of the substrate.

[0015] The chip card module may optionally include one and / or another of the following features, each of which is considered independently of each other, or in combination with one or more other features:

[0016] - The sensor is fixed to the inner side of the dielectric substrate using an adhesive layer with a thickness between 5 and 35 micrometers; and

[0017] - The module has a first connection pad and a second connection pad, wherein the first connection pad is electrically connected to the sensor and is located below the package, and the second connection pad is electrically connected to the first connection pad. These second pads are designed to connect the module to the chip card circuit and are located outside the package.

[0018] According to another aspect, the present invention relates to a chip card including a biometric identification sensor module according to the invention. The chip card includes a card body having circuitry integrated within it. The module and circuitry are electrically connected to each other using solder deposited on connection pads.

[0019] According to another aspect, the present invention relates to a method for manufacturing a biometric identification sensor module for a chip card, comprising the following steps:

[0020] - A dielectric substrate having an outer side and an inner side is provided, wherein the outer side and the inner side are each located on one side of the dielectric substrate along the thickness of the dielectric substrate, and the inner side and the outer side of the substrate correspond to the main surface of the substrate.

[0021] - Before or after fixing the conductive material foil layer to the inner side of the substrate, traces and bonding pads are formed in the conductive material foil layer;

[0022] - A biometric sensor with a detection element formed by a sensitive element is fixed to an area on the inner side that does not have any conductive material, and the area on the outer side opposite to the detection element corresponds to the biometric detection area.

[0023] - Connect the sensor to at least some solder pads; and

[0024] - Encapsulate the sensor within a package.

[0025] In addition, the outer surface of the substrate includes exposed homogeneous polymer material in at least the detection area. Attached Figure Description

[0026] Other aspects, objects, and advantages of the invention will become apparent from the following detailed description and with reference to the accompanying drawings, which are given by way of non-limiting example, in which:

[0027] Figure 1 A perspective view of a chip card according to an example of an embodiment of the present invention is shown schematically;

[0028] Figures 2a to 2d The diagram schematically illustrates cross-sectional views of various steps in an example of a method for manufacturing a biometric sensor module, such as one integrated into... Figure 1 The module in the card shown; and

[0029] Figure 3 Schematic illustration of using, such as Figures 2a to 2d A cross-sectional view of the integration of the biometric sensor module into the card obtained by the method shown. Detailed Implementation

[0030] Figure 1 An example of a chip card 1 according to the present invention is shown. In this example, card 1 is an ID-1 format bank card. Card 1 has a first module 2, which includes a connector 3 and an electronic chip (below the connector). The connector 3 enables the electronic chip to be electrically connected to a card reader for exchanging data between the chip and the card reader.

[0031] In the case of a dual-interface card, that is, one that allows for both contact and contactless reading, card 1 also has an antenna integrated into the card body. This antenna is connected to a chip located, for example, within the first module 2. This antenna allows for contactless data exchange between the chip and the contactless card reader. The antenna, or another part of the circuitry located within the card body, is also electrically connected to a second module 4 integrated into card 1. The second module 4 is a biometric identification module. This biometric identification module 4 includes a sensor for fingerprint recognition. The second module 4 enables the determination of whether the fingerprint read by the sensor corresponds to the fingerprint of a user authorized to use card 1. In this case, contactless communication between the chip and the reader can be authorized.

[0032] The following describes an example of a method for manufacturing the type of module shown in Figure 2.

[0033] The method includes providing a composite material 100, which includes a substrate 101 made of a dielectric material, on which a foil layer composed of a conductive material 102 is laminated (see [link to documentation]). Figure 2a For example, the dielectric material is a polyimide with a thickness between 25 and 75 micrometers, and preferably a thickness of 50 micrometers, and the first conductive material 102 is made of copper or a copper alloy, with a thickness between 12 and 70 micrometers, and preferably equal to 18 micrometers. To effectively implement the method according to the invention on an industrial scale, the composite material 100 is advantageously provided in rolls, and the method is implemented in a roll-to-roll manner. The composite material 100 can be provided in the form of a foil-clad laminate, such as a copper-clad laminate. Alternatively, it can be provided in the form of a multilayer composite 100 (not shown), comprising a dielectric material substrate 101, a conductive material foil layer 102, and an adhesive material layer (e.g., an epoxy resin material) between the dielectric material substrate 101 and the conductive material foil layer 102. The adhesive material has a thickness, for example, between 10 and 25 micrometers. The multilayer composite 100 is laminated. The adhesive material can be subjected to a continuous drying process to remove solvents present in the formulation during deposition. Therefore, the adhesive layer allows the conductive foil layer 102 to be fixed to the inner surface of the dielectric substrate 101. A thermal crosslinking step of the adhesive material can then be performed after lamination.

[0034] The polyimide forming substrate 101 is, for example, a heat-stable polyimide (such as an aromatic polyimide). For example, DuPont... TM (DuPont TM For sale B Black or For Sale KYPI-B.

[0035] The next step is photolithography, which is used to form bonding pads and traces 7 in the conductive material foil layer 102 (see [link]). Figure 2b These steps include laminating a photosensitive resin dry film onto a blank surface, such as a conductive material foil layer 102, and subsequently insulating the photosensitive resin dry film through a mask, exposing the photosensitive resin, and etching certain areas of the conductive material foil layer 102 to form bonding pads, bonding traces, or any other form of conductive structure 7 for the circuit board.

[0036] Alternatively, the bonding pads and traces 7 are formed by cutting or etching the conductive material foil layer 102 (using lead frame technology) before laminating them onto the inner side of the dielectric substrate 101.

[0037] Advantageously, it is feasible to perform electrolytic deposition of a metal layer 107 (e.g., copper, nickel, gold, palladium, silver, and alloys thereof), the electrolytic deposition of which is intended to facilitate soldering of the connecting wire 11 to the conductive material 102 (see [link to documentation]). Figure 2c Other conceivable techniques for connecting sensor 300 to the bonding pad and trace 7 may also require one or more metallization steps.

[0038] More specifically, the bonding pads and traces 7 form a circuit including a first bonding pad and a second bonding pad. The first bonding pad is electrically connected to the sensor 300 and located below the package 12, and the second bonding pad is electrically connected to the first bonding pad. These second bonding pads are designed to connect the module 4 to the chip card circuit 200. These second bonding pads are located outside the package 12 (see further reference below). Figure 2d (Description). It is feasible to connect the first and second pads via conductor traces to establish the required electrical connection between the inside and outside of package 12.

[0039] According to a specific embodiment of the method of the present invention, solder 6 is deposited in the preceding steps (see...). Figure 2d The solder 6 is applied to the bonding pads 7 formed in the conductive material foil layer 102. For example, the solder 6 is a tin-bismuth or tin-bismuth-silver alloy.

[0040] Instead of depositing solder 6 onto the bonding pads 7, these bonding pads 7 are left undeposited before the module 4 is embedded into the card 1. Then, during the embedding operation, before inserting the module 4 into the cavity 208 formed in the card body (e.g., by milling), solder 6, paste, or anisotropic conductive film 6' is deposited on the bonding pads 7 to establish a connection with the circuitry 200 mounted in the card body (see...). Figure 3 ).

[0041] At the end of the above steps, a roll of material including biometric sensor supports for chip cards is obtained. Each of these supports has a corresponding, for example... Figure 2d The structure is shown. Therefore, each support includes:

[0042] - The outer surface of the detection area 108 is located opposite to the area of ​​the sensitive element of the detection element of the biometric sensor to be placed on the inner surface;

[0043] - The inner surface of the connection pads 7 may have clumps of solder 6 deposited on at least some of these connection pads 7, so that the module 4 can subsequently be connected to the circuitry 200 integrated into the card body (see...). Figure 3 ).

[0044] For use and integration into chip card 1, each support is equipped with a biometric fingerprint sensor 300. Advantageously, the biometric sensor 300 is insensitive to electrostatic charge or only slightly sensitive. Therefore, a bezel can be eliminated. This method is thus significantly simplified compared to prior art methods in which a bezel must be manufactured on the outer surface and then electrically connected (e.g., using vias) to circuitry on the inner surface.

[0045] The biometric sensor 300 is attached to the back side using, for example, a known die-attachment technique. For instance, a thermosetting adhesive 400 is used to attach the biometric sensor 300 to the back side of the support 101. This thermosetting adhesive 400 is set at a temperature between 100°C and 150°C and has the property of migrating under the entire surface of the sensor via capillary action without creating any gaps or bubbles (“insufficient filling”). For example, the thickness of the thermosetting adhesive 400 beneath the biometric sensor 300 is between 5 micrometers and 35 micrometers. The thermosetting adhesive is, for example, an adhesive containing amine groups and without any epoxy resin.

[0046] Solder 6 may be deposited on the bonding pad 7 before or after assembling the biometric sensor 300, but it is preferred to deposit solder 6 on the bonding pad 7 after assembling the biometric sensor 300 to avoid the solder 6 (especially if the solder 6 is a low-temperature solder) melting during the crosslinking of the thermosetting adhesive 400.

[0047] Solder 6 is deposited by screen printing or by spraying. If the biometric sensor 300 has been assembled to the dielectric support 101, solder 6 is preferably deposited on the bonding pad 7 by spraying.

[0048] The biometric sensor 300 occupies a surface area on the back side that substantially corresponds to the area on the inner side of the dielectric substrate 101 opposite to the detection area 108. The biometric sensor 300 is connected to the bonding pad 7 using known techniques, such as wire bonding using wires 11. Figure 2d and Figure 3 As shown. Alternatively, flip-chip technology is used to connect the biometric sensor 300 to the bonding pad 7. Advantageously, the biometric sensor 300 and its possible wires 11 are protected within a package 12, which is made of, for example, encapsulating resin. A hot melt adhesive 10 can also be disposed on or near the back of the bonding pad 7. This hot melt adhesive 10 is intended to secure the biometric sensor module 4 within the cavity 208 formed in the chip card body (see...). Figure 3 ).

[0049] When module 4 is embedded in the card body, several feasible options exist for establishing a connection between the connection pads 7 of module 4 and the circuitry 200 integrated in the card body. For example, the connection pads 7 can be directly soldered to the circuitry 200 using solder 6 deposited on them. Alternatively, clumps 206 of solder can be deposited on the circuitry 200 to form a circuit between the solder pads 7 and the circuitry 200 by melting one or more solders pre-deposited on the connection pads 7 and the circuitry 200, respectively. More specifically, for example, a first solder 6 can be deposited on the connection pads 7, and a second solder 206 can be deposited on the circuitry 200. The first solder 6 is advantageously a solder with a low melting temperature (e.g., a melting temperature below or equal to 140°C), and the second solder 206 is advantageously a melting temperature close to or equal to that of the first solder 6.

[0050] For example, in order to connect the bonding pad 7 to the circuit 200, the hot electrode 500 is placed facing the bonding pad 7 on either side of the support 101.

[0051] A first solder 6 with a low melting temperature (below or equal to 140°C) is used on the bonding pad 7, and a second solder 206 with a melting temperature equal to, close to, or lower than that of the first solder 6 is used on the circuit 200. A heating electrode 500 heated to, for example, 230°C is applied for up to 1.5 seconds. Therefore, in this case, the method according to the invention is faster. Furthermore, the use of solders 6 and 206 with low melting temperatures allows for the use of heating electrodes 500 with smaller carrier surfaces, thereby helping to better control creep and limit the risk of deformation of card 1 and / or module 4. This method of using low-temperature solder 206 is advantageous for card bodies, for example, made of PVC, when the lamination temperature of the circuit 200 and solder 206 in the card does not exceed 130°C.

[0052] A first solder 6 with a low melting temperature (below or equal to 140°C) is used on the bonding pad 7, and a second solder 206 with a higher melting temperature is used on the circuit 200. A hot electrode 500 heated to, for example, 230°C is applied for up to 2.5 seconds. The heat provided by the hot electrode 500 is also dissipated into the hot melt adhesive 10, thereby bonding the module 4 to the card 1.

[0053] This method of using solder 206 with a high melting temperature is advantageous for card bodies, for example, when the lamination temperature of the circuit 200 in the card and its solder 206 can be in the range of up to 190°C.

[0054] Generally, the module 4 can be connected to the circuit 200 using conductive adhesive or paste 6', anisotropic conductive film, or solder 6. However, in any case, the above-described methods and variations can be advantageously used by manufacturing connection pads 7 with shapes compatible with the use of solder 6 and with the paste or anisotropic conductive film 6', the shapes being rectangular, rhomboid, square, elliptical, or dish-shaped, and capable of radial or lateral extension. The module 4 according to the invention is then connected regardless of whether it is soldered or using conductive adhesive. This allows for the manufacture of the module 4 in high production volumes while still allowing the installer to choose one connection technology or another.

[0055] For aesthetic reasons and / or to indicate the location of the detection area, where a finger should be placed on the detection area for fingerprint detection, the dielectric substrate 101 is advantageously integrally colored. For example, the dielectric substrate 101 is a polyimide colored black using pigments or dyes.

Claims

1. A biometric identification sensor device for a chip card (1), comprising: - Dielectric substrate (101), the dielectric substrate having an outer side and an inner side, wherein the outer side and the inner side are respectively located on one side of the dielectric substrate (101) along the thickness of the dielectric substrate, and the inner side and the outer side of the dielectric substrate (101) correspond to the main surface of the dielectric substrate. - Traces and bonding pads (7) formed in a conductive material foil layer (102), the conductive material foil layer being laminated onto the inner side of the dielectric substrate (101) and fixed to the inner side of the dielectric substrate (101); - A biometric sensor (300) having a detection element formed of a sensitive element, the sensor (300) being attached to a back surface opposite to an adhesive layer, a plurality of connecting wires of the sensor (300) being connected to at least a plurality of connecting pads (7), and the sensor (300) itself being fixed to an area on an inner surface that has no conductive material, the area on the outer surface opposite the detection element corresponding to a biometric detection area (108), the biometric detection area (108) being configured such that a finger placed thereon establishes communication with the detection element; and - Package (12), said package being deposited on at least one side of the inner surface of the dielectric substrate (101) of the sensor (300) and the plurality of connecting lines, - wherein the outer surface of the dielectric substrate (101) is made of a homogeneous polymer material in at least the detection area (108), the homogeneous polymer material being exposed and having a glass transition temperature greater than or equal to 110 degrees Celsius, wherein the homogeneous polymer material has a thickness between 25 micrometers and 75 micrometers, and the adhesive layer has a thickness between 5 micrometers and 35 micrometers.

2. The apparatus according to claim 1, characterized in that, The homogeneous polymer material is selected from the following materials: polyimide, polyethylene naphthalate, and polyetheretherketone.

3. The apparatus according to any one of claims 1-2, characterized in that, The homogeneous polymer material has a thickness of 50 micrometers.

4. The apparatus according to any one of claims 1-2, characterized in that, The homogeneous polymer material is colored in an overall distributed manner.

5. The apparatus according to any one of claims 1-2, characterized in that, The device has a first connection pad and a second connection pad, wherein the first connection pad is electrically connected to the sensor (300) and located below the package (12), and the second connection pad is electrically connected to the first connection pad. These second connection pads are intended to connect the device (4) to the chip card circuit (200) and located outside the package (12).

6. The apparatus according to any one of claims 1-2, characterized in that, The outer surface does not have a border surrounding the detection area (108).

7. A chip card, characterized in that, The device includes a card body and a device (4) according to any one of claims 1-6, the card body having circuitry (200) integrated within the card body, the device (4) and the circuitry (200) being electrically connected using solder (6, 6') deposited on a second connection pad.

8. A method for manufacturing a biometric identification sensor device (4) for a chip card (1), comprising the following steps: - A dielectric substrate (101) having an outer side and an inner side is provided, wherein the outer side and the inner side are respectively located on one side of the dielectric substrate (101) along the thickness of the dielectric substrate, and the inner side and the outer side of the dielectric substrate (101) correspond to the main surface of the dielectric substrate. - Before or after laminating the conductive material foil layer (102) onto the inner side of the dielectric substrate (101), traces and bonding pads (7) are formed in the conductive material foil layer (102); - A biometric sensor (300) having a detection element formed by a sensitive element is fixed to an area on the inner side that does not have any conductive material. An area on the outer side opposite to the detection element, corresponding to the biometric detection area (108), is configured such that a finger placed thereon establishes communication with the detection element. The biometric sensor is fixed to the inner side of the dielectric substrate with an adhesive layer having a thickness between 5 micrometers and 35 micrometers. - The sensor (300) is connected to at least some bonding pads (7) using multiple connecting wires connected to the opposite back sides of the adhesive layer; and - The sensor (300) and the plurality of connecting wires are encapsulated in a package (12). -The outer surface of the dielectric substrate (101) is made of a homogeneous polymer material in at least the detection area (108), the homogeneous polymer material being exposed and having a glass transition temperature greater than or equal to 110 degrees Celsius, wherein the homogeneous polymer material has a thickness between 25 micrometers and 75 micrometers, and the adhesive layer has a thickness between 5 micrometers and 35 micrometers.

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