SURFACE SENSOR

• US 20130194071A1
• Filed: 12/28/2010
• Published: 08/01/2013
• Est. Priority Date: 12/29/2009
• Status: Active Grant

• Current Assignee: IDEX Biometrics ASA
• Original Assignee: Idex ASA
• Inventors: Bredholt, Geir Ivar, Christie, Nicolai W., Bernstein, Ralph W., Slgedal, yvind, Ntas, Anders
• Granted Patent: US 9,122,901 B2
• Time in Patent Office: Days
• US Class Current: 340/5.82
• CPC Class Codes: G06K 19/07701 the record carrier comprising an interface suitable for human interaction
• CPC Class Codes: G06V 40/1306 non-optical, e.g. ultrasonic or capacitive sensing
• CPC Class Codes: G06V 40/1312 direct reading, e.g. contactless acquisition
• CPC Class Codes: G06V 40/1329 Protecting the fingerprint sensor against damage caused by the finger
• CPC Class Codes: H01L 2224/16227 the bump connector connecting to a bond pad of the item
• CPC Class Codes: H01L 2224/16235 the bump connector connecting to a via metallisation of the item
• CPC Class Codes: H01L 2924/15192 Resurf arrangement of the internal vias
• CPC Class Codes: H01L 2924/15311 being a ball array, e.g. BGA
• CPC Class Codes: H01L 2924/15321 being a ball array, e.g. BGA

Abstract

The invention relates to a sensor for detection of properties and structures of an organic tissue and its surface, e.g. a fingerprint sensor comprising a chosen number of sensor electrodes at chosen positions for coupling to a finger tissue and its surface having a size less or comparable to the size of the structures, characteristics or properties of the finger tissue or surface, and a processing unit including electronic circuitry connected to said electrodes for detection of the voltage at, or the current flow in the electrodes, thereby providing for detection and collection of information of related capacitance, impedance, electromagnetic field, fingerprint, tissue aliveness or other biometric, physical, physiological, thermal or optical or characteristics or properties of the tissue or its surface positioned over the electrodes, the processing unit being mounted on one side of a substrate and the electrodes being embedded in said substrate, the substrate including through going first, second and third conductive paths between said sensor electrodes and said measurement circuitry. The substrate is made from a polymer material such as Polyimide, implemented as a rigid or a flexible multi layer build-up substrate, said first, second, and third conductive paths are constituted by through going substrate sections of a chosen size and material.

Claims

1. A sensor unit for measuring structures and properties by the surface of an object of organic tissue, especially a fingerprint sensor, the sensor comprising:

a contact surface adapted to have mechanical contact with said object;

a first dielectric layer having a chosen thickness;

a second dielectric layer covered by said first layer also including;

a number of electrically conductive first and second electrodes having predetermined sizes and positions on the same side of the layer as the first layer; and

a number of conductive sections separated by the dielectric material in said layer, each conductive section having a first end galvanically coupled one of said first and second electrodes and a second end having predetermined positions on a reverse side of said second dielectric layer;

electrically conductive connecting means connected to said conductive sections at said predetermined positions of said second ends of the conductive sections for galvanic connection to a signal processing unit, said electrically conductive connecting means being positioned in positions laterally separated from the position of said electrodes;

said signal processing unit being adapted to detect a voltage or current at said first and second electrodes; and

wherein the dielectric material in said layers are flexible materials.

2. The sensor unit according to claim 1, wherein the dielectric material is polyimide.

3. The sensor unit according to claim 1, comprising an additional layer constituted by at least two sub-layers where at least one comprises a pattern of conductive sections adapting the positions of the second conductor ends to the required positions of connection points to a processing unit.

4. The sensor unit according to claim 1, wherein the contact surface is provided with a protecting coating.

5. The sensor unit according to claim 1, wherein the opposite side relative to the contact surface is coated with a hardened material.

6. The sensor unit according to claim 5, wherein the hardened material also covers a mounted processing unit.

7. The sensor unit according to claim 1, wherein at least one of said second electrode having dimensions being larger than the structures of the surface to be measured, said additional layer including conductive sections extending from the electrode to the opposite side of the sensor unit.

8. The sensor unit according to claim 7, wherein the second electrode is provided with a connection point at said opposite side for coupling to the processing unit.

9. The sensor unit according to claim 7, wherein the thickness of the first layer over at least one second electrode is reduced.

10. The sensor unit according to claim 1, wherein the first layer comprises openings over at least one of said electrodes providing galvanic contact between the electrode and the object.

11. The sensor unit according to claim 1, wherein said coupling means are connected to conductors on a flexible PCB or printed circuit, the conductors providing a connection between the coupling means and a corresponding interface on a signal processing unit positioned in a position laterally separated from the coupling means.

12. The sensor unit according to claim 11, wherein the processing unit is positioned on the same side of the flexible PCB or printed circuit relative to the coupling means.

13. The sensor unit according to claim 11, wherein the processing unit is positioned on the opposite side of the flexible PCB or printed circuit relative to the coupling means.

14. The sensor unit according to claim 11, wherein the flexible PCB or printed circuit comprises a number of components and a coupling interface to external equipment.

15. A method for producing a sensor unit according to claim 1, comprising the steps of:

depositing liquid polyimide on a plane glass surface and hardening the polyimide material;

depositing a second layer on said first layer by applying a pattern of electrically conductive material constituting first electrodes on the first layer and depositing a liquid polyimide layer thus providing an insulation between the first electrodes and hardening the polyimide material;

depositing the third layer by applying a pattern of electrically conductive material constituting a number of conductors having one end electrically connected to said pattern of electrically conductive material in said second layer, and depositing a liquid polyimide layer thus providing an insulation between the first electrodes and hardening the polyimide material; and

removing the abovementioned layers from said glass surface, so as to prove said contact surface at the earlier contact surface between said glass surface and said first layer.

16. The method according to claim 11, including a step of applying an electrically conductive material on the second ends of the conductive sections for providing connecting means.

17. The sensor unit according to claim 4, wherein the protecting coating comprises a carbon based material.

18. The sensor unit according to claim 5, wherein the hardened material comprises a resin material.