BIOMETRIC IMAGING MODULE AND METHOD FOR MANUFACTURING A BIOMETRIC IMAGING MODULE

Abstract

Method for manufacturing a biometric imaging module, the method comprising: providing a carrier tape; forming a sensor opening and at least one contact pad opening in the carrier tape, wherein the sensor opening is adjacent to the contact pad opening; and from a top side of the carrier tape, arranging a biometric sensor on the carrier tape such that a body of the biometric sensor is arranged in the sensor opening and a conductive contact pad of the biometric sensor is aligned with and accessible through the contact pad opening from a backside of the carrier tape, and such that a sensing surface of the biometric sensor is facing in the same direction as the top side of the carrier tape.

Claims

1. Method for manufacturing a biometric imaging module, the method comprising: providing a carrier tape; forming a sensor opening and at least one contact pad opening in the carrier tape, wherein the sensor opening is adjacent to the contact pad opening; and from a top side of the carrier tape, arranging a biometric sensor on the carrier tape such that a body of the biometric sensor is arranged in the sensor opening and a conductive contact pad of the biometric sensor is aligned with and accessible through the contact pad opening from a backside of the carrier tape, and such that a sensing surface of the biometric sensor is facing in the same direction as the top side of the carrier tape.

2. The method according to claim 1, further comprising depositing a glue layer on a top side of carrier tape prior to forming the sensor opening and contact pad opening and fixing the biometric sensor to the carrier tape by means of the glue layer.

3. The method according to claim 2, wherein the glue layer is deposited through lamination of a glue film to the top side of the carrier film.

4. The method according to claim 1, wherein arranging the biometric sensor on the carrier tape comprises fixing the biometric sensor to the carrier tape by means of hot stamping.

5. The method according to claim 1, wherein the contact pad opening is separate from the sensor opening.

6. The method according to claim 1, wherein the biometric sensor comprises a cover structure arranged to cover the sensor body, the conductive contact pad being arranged on the cover structure, and wherein a portion of the cover structure is arranged and configured to extend past the contact pad.

7. The method according to claim 1, wherein the sensor body is arranged to protrude below a bottom surface of the carrier tape.

8. The method according to claim 1, wherein the carrier tape is a flexible reel-to-reel-type film.

9. The method according to claim 1, further comprising depositing a glue layer on a bottom side of the carrier tape.

10. The method according to claim 1, further comprising punching out the biometric imaging module from the carrier tape.

11. The method according to claim 1, further comprising arranging the biometric imaging module in an opening of a smart card and forming an electrical connection between the biometric sensor and smartcard circuitry by means of the conductive contact pad.

12. The method according to claim 11, further comprising soldering contacts of the smart card to the conductive contact pad, wherein the contact pad opening of the carrier tape constrains the soldering area.

13. A biometric imaging module comprising a carrier tape comprising a sensor opening and a contact pad opening, wherein the sensor opening is adjacent to the contact opening; a biometric sensor attached to a first side of the carrier tape such a body of the biometric sensor is located in the sensor opening of the carrier tape, wherein the biometric sensor comprises an active sensing area facing in the same direction as the first side of the carrier tape, the biometric sensor further comprising a conductive contact pad aligned with the contact pad opening and accessible from a second side of the carrier tape, the second side being opposite the first side.

14. The biometric imaging module according to claim 13, wherein the contact opening is separate from the sensor opening.

15. The biometric imaging module according to claim 13, wherein the body of the biometric sensor is arranged to protrude through the carrier tape on the second side of the carrier tape.

16. The biometric imaging module according to claim 13, wherein the biometric sensor comprises a cover structures arranged to cover the sensor body, and wherein a sensing surface is formed by an exterior surface of the cover structure.

17. The biometric imaging module according to claim 13, wherein the cover structure is larger than the sensor module body, and wherein the conductive contact pad is arranged on the cover structure.

18. A smartcard comprising a biometric imaging module according to claim 13, wherein the conductive contact pad of the biometric imaging module is arranged in contact with a conductive trace of the smartcard.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] These and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing an example embodiment of the invention, wherein:

[0024] FIG. 1 is a flow chart outlining general steps of the method according to an embodiment of the invention;

[0025] FIGS. 2A-D schematically illustrate steps of a method according to an embodiment of the invention;

[0026] FIGS. 3A-B are schematic perspective views of a biometric imaging module according to an embodiment of the invention;

[0027] FIG. 4 schematically illustrate a biometric imaging module according to an embodiment of the invention; and

[0028] FIG. 5 schematically illustrates a biometric imaging module integrated in a smartcard according to an embodiment of the invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0029] In the present detailed description, various embodiments of the method for manufacturing an image module and the biometric image module according to the present invention are mainly described with reference to a capacitive fingerprint sensing device for integration in a smartcard. However, the described method is equally applicable for other types of biometric sensors and for other applications such as IoT devices and the like.

[0030] FIG. 1 is a flow chart outlining general steps of the method, and the method will be described with further reference to FIGS. 2A-D illustrating various steps of the method.

[0031] The first step comprises providing 100 a carrier tape 200. The carrier tape 200 is preferable provided in the form of a flexible reel-to-reel type film acting as the carrier tape.

[0032] The method further comprises depositing 102 a glue layer 211 on a top side 208 of the carrier tape 200, wherein the glue layer 211 is preferably deposited through lamination of a glue film 211 to the top side 208 of the carrier film 200. The next step comprises forming 104 a sensor opening 204 and at least one contact pad opening 206 in the carrier tape 200, wherein the sensor opening 204 is adjacent to the contact pad openings 206 as illustrated in FIG. 2A showing first a side view and secondly a view from the bottom side 210 of the carrier tape 200. The required openings are thereby formed in the glue layer 211 as well as in the carrier tape 200, preferably by punching out the opening using an appropriate tool. In the example illustrated in FIG. 2A the carrier film comprises four separate contact pad openings 206 with one opening 206 on each side of the rectangular sensor opening 204. The smaller conductive pad openings 206 may also be located closer to the sensor opening 204

[0033] Next, a biometric sensor 212 is arranged 106 on the carrier tape 200 from the top side 208 of the carrier tape and fixed to the carrier tape 200 by means of the glue layer 208. Instead of using a glue layer, it would be equally possible to fix the biometric sensor to the carrier tape by means of so-called hot stamping. In a hot stamping technique, the carrier tape 200 itself is made from a thermoplastic material or a B-stage epoxy. When the biometric sensor 212 is placed onto the carrier tape 200 using a holder, both a pressing force and heat are applied via the holder so that the biometric sensor 212 becomes firmly fixed in the correct position in relation to the carrier tape 200.

[0034] The biometric sensor 212 is placed such that a body 214 of the biometric sensor 212 is located in the sensor opening 204 and the conductive contact pads 216 of the biometric sensor 212 are aligned with and accessible from the bottom side 210 of the carrier tape through the corresponding contact pad openings 206 of the carrier tape 200. A sensing surface 219 of the biometric sensor 212 is facing in the same direction as the top side 208 of the carrier tape 200. The top and bottom sides 208, 210 of the carrier tape 200 are defined in relation to the biometric sensor 212 such that the sensing surface 219 of the biometric sensor 212 is facing in the same direction as the top side 208 of the carrier tape 200.

[0035] The conductive contact pads 216 of the biometric sensor 212 are configured to form an electrical connection between the biometric sensor 212 and external circuitry, such as circuitry in a smart card, so that the biometric sensor 212 can be used e.g. for authentication of a user of the smartcard. Moreover, the biometric sensor 212 comprises an electrically conductive bezel 221 which is accessible from the top side of the biometric sensor 212 and which is located adjacent to the sensing surface 219. The bezel is used to control the electric potential of a finger in contact with the biometric sensor 212 which is advantageous in capacitive sensing methods. However, the described bezel is not strictly required for the overall functionality of the sensor and is therefore optional.

[0036] The biometric sensor further comprises a cover structure 218 arranged to cover the sensor body 214 as can be seen in FIGS. 2B-D. The cover structure 218 can be made from materials used for PCBs (printed circuit boards) using a glass fiber core or from PI (polyimide) materials without glass fiber. The sensing surface 219 is thereby formed by the top surface of the cover structure 218 and the conductive contact pad 216 is arranged on the bottom surface of the cover structure, and wherein a portion of the cover structure is arranged and configured to be larger than the sensor body 214 and to extend past the contact pad 216.

[0037] FIG. 2C illustrates that a glue layer 220 (hot-melt) is deposited on the backside 210 of the carrier film in preparation for arranging the biometric sensor module in a smartcard. The hot-melt layer 220 may be deposited on the backside 210 of the carrier tape 200 by lamination, and the openings of the hot-melt layer 220 are formed before lamination. The openings in the hot-melt layer 220 are preferably punched out of the layer in a similar way as the openings of the carrier tape 200 are formed.

[0038] In FIG. 2d, the biometric sensor 212 is punched out from the carrier film 200 to form a T-shaped biometric sensor module 222 suitable for smartcard integration.

[0039] FIG. 3 is a perspective view of the biometric sensor module 222 as seen from above illustrating the sensing surface 219 and the bezel 221.

[0040] FIG. 4 is a schematic illustration of an embodiment where there is no carrier tape between the conductive pad openings 206 and the sensor opening 204. In other words, the contact pad opening 206 can be seen as a cutout of the sensor opening 204. As can be seen, there is still a separation between the contact pads 206 and the sensor body 214.

[0041] FIG. 5 illustrates the assembly of a T-shaped biometric sensor module 222 in a smart card 300. The smart card 300 comprises a recess 302 having a T-shape corresponding to the T-shape of the sensor module 222. Here it can be seen that conducive contact pads 216 of the biometric sensor module 222 are located such that they can form an electrical connection with corresponding connections 304 of the smart card 300. The biometric sensing module 200 is advantageously attached to the smart card substrate using an adhesive with solder material at the locations of the connections 304. The electrical path is formed from the biometric sensor 212 through the conductive contact pads 216 on the cover structure 218 and via solder joints to wires 306 in the card body 308. Mechanical adhesion can be enabled by the so called “hot-melt” (a thermoplastic adhesive, 220) arranged between the extending portion of the cover structure 218 of the biometric imaging module 222 and the card body 308.

[0042] The recess 224 formed by the remaining carrier film 200 in the biometric imaging module can thereby assist the soldering process by preventing the solder from flowing away from the conductive contact pads 216. Thereby, the risk of electrical short circuits and of solder contamination is reduced, improving the overall quality of the soldering step. Furthermore, the fingerprint sensor module 200 can be placed in the smart card 300 using a hot-stamping process.

[0043] Even though the invention has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art. Also, it should be noted that parts of the method and imaging module may be omitted, interchanged or arranged in various ways, the imaging module yet being able to perform the functionality of the present invention.

[0044] Additionally, variations to the disclosed embodiments can be understood and effected by the skilled person in practicing the claimed invention, from a study of the drawings, the disclosure, and the appended claims. In the claims, the word “comprising” does not exclude other elements or steps, and the indefinite article “a” or “an” does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.