Surface sensor

Abstract

The application relates to a fingerprint sensor assembly for detection of properties or structure of a finger at chosen positions. The fingerprint sensor assembly includes a plurality of sensor electrodes, a processing unit, a dielectric substrate, and a plurality of conductive paths. The dielectric substrate is between the plurality of sensor electrodes and the processing unit. The first plurality of conductive paths is associated with the plurality of sensor electrodes, where each of the plurality of conductive paths includes at least a portion extending through the dielectric substrate and provides an electrical connection between one of the plurality of sensor electrodes and the processing unit. The processing unit is configured to detect a signal at each of the plurality of sensor electrodes. The plurality of sensor electrodes is embedded in the dielectric substrate.

What is claimed is: 
     
         1 . A fingerprint sensor assembly comprising:
 a plurality of sensor electrodes;   a processing unit;   a dielectric substrate between the plurality of sensor electrodes and the processing unit; and   a plurality of conductive paths associated with the plurality of sensor electrodes, each of the plurality of conductive paths including at least a portion extending through the dielectric substrate and providing an electrical connection between one of the plurality of sensor electrodes and the processing unit,   wherein the processing unit is configured to detect a signal at each of the plurality of sensor electrodes, and   wherein the plurality of sensor electrodes is embedded in the dielectric substrate.   
     
     
         2 . The fingerprint sensor assembly of  claim 1 , further comprising:
 a plurality of electrically conductive components connected to the plurality of conductive paths,   wherein the plurality of conductive paths are located between the plurality of sensor electrodes and the plurality of electrically conductive components, and   wherein each of at least a subset of the plurality of electrically conductive components is offset, in a direction perpendicular to the conductive paths, from a center of a sensor electrode electrically connected to the electrically conductive component.   
     
     
         3 . The fingerprint sensor assembly of  claim 2 , further comprising an additional dielectric substrate located directly on top of the dielectric substrate. 
     
     
         4 . The fingerprint sensor assembly of  claim 2 , wherein each of the plurality of conductive paths is less wide than a sensor electrode to which the conductive path is electrically connected. 
     
     
         5 . The fingerprint sensor assembly of  claim 4 , further comprising a shield layer embedded in the dielectric layer and positioned between the sensor electrodes and the electrically conductive components, wherein the shield layer is electrically connected to ground potential and is adapted to protect the electrically conductive components against inductive or capacitive coupling with the sensor electrodes. 
     
     
         6 . The fingerprint sensor assembly of  claim 1 , wherein the sensor electrodes are embedded below a first surface of the dielectric substrate, and wherein the processing unit is located below a second surface of the dielectric substrate, the second surface being opposite the first surface. 
     
     
         7 . A fingerprint sensor assembly comprising:
 a plurality of sensor electrodes;   a processing unit;   a dielectric substrate between the sensor electrodes and the processing unit; and   a plurality of conductive paths associated with the plurality of sensor electrodes, each of the plurality of conductive paths including at least a portion extending through the dielectric substrate and providing an electrical connection between one of the plurality of sensor electrodes and the processing unit,   wherein the processing unit is configured to detect a signal at each of the plurality of sensor electrodes, and   wherein the processing unit is embedded in the dielectric substrate.   
     
     
         8 . The fingerprint sensor assembly of  claim 7 , further comprising an additional dielectric substrate located directly on top of the dielectric substrate. 
     
     
         9 . The fingerprint sensor assembly of  claim 8 , wherein the dielectric substrate has a first surface and a second surface opposite the first surface, wherein the processing unit is embedded within the second surface, the sensor assembly further comprising a plurality of electrically conductive coupling points located at the second surface of the dielectric substrate and forming an interface for any device outside the dielectric substrate to electrically connect to the processing unit. 
     
     
         10 . The fingerprint sensor assembly of  claim 8 , wherein the plurality of electrically conductive coupling points includes a ball grid array (BGA) interface. 
     
     
         11 . The fingerprint sensor assembly of  claim 8 , further comprising:
 a plurality of electrically conductive components connected to the plurality of conductive paths, wherein the plurality of conductive paths are located between the plurality of sensor electrodes and the plurality of electrically conductive components; and   a shield layer embedded in the dielectric substrate and positioned between the sensor electrodes and the electrically conductive components, wherein the shield layer is electrically connected to ground potential and is adapted to protect the conductive components against inductive or capacitive coupling with the sensor electrodes.   
     
     
         12 . A fingerprint sensor assembly comprising:
 a plurality of sensor electrodes;   a processing unit;   a dielectric substrate between the sensor electrodes and the processing unit; and   a plurality of conductive paths associated with the plurality of sensor electrodes, each of the plurality of conductive paths including at least a portion extending through the dielectric substrate and providing an electrical connection between one of the plurality of sensor electrodes and the processing unit; and   a resin layer in contact with the dielectric substrate,   wherein the processing unit is configured to detect a signal at each of the sensor electrodes, and   wherein the processing unit is embedded in the resin layer.   
     
     
         13 . The fingerprint sensor assembly of  claim 12 , wherein the resin layer is a cured resin layer. 
     
     
         14 . The fingerprint sensor assembly of  claim 12 , further comprising:
 a plurality of electrically conductive components embedded in the dielectric substrate and electrically connected to at least a subset of the plurality of conductive paths;   a plurality of conductive coupling points located at an interface between the dielectric substrate and the resin layer,   wherein the plurality of conductive coupling points provide electrical connection between the electrically conductive components and the processing unit.   
     
     
         15 . The fingerprint sensor assembly of  claim 14 , further comprising an additional dielectric substrate located directly on top of the dielectric substrate. 
     
     
         16 . A fingerprint sensor assembly comprising:
 a plurality of sensor electrodes;   a processing unit;   a dielectric substrate between the sensor electrodes and the processing unit; and   a first plurality of conductive paths associated with the plurality of sensor electrodes, each of the plurality of conductive paths including at least a portion extending through the dielectric substrate and providing an electrical connection between one of the plurality of sensor electrodes and the processing unit;   a circuit board having a first surface on which the dielectric substrate is directly or indirectly mounted, and a second surface on which the processing unit is mounted, wherein the first surface is opposite to the second surface;   a second plurality of conductive paths extending through the circuit board and electrically connected to at least a subset of the first plurality of conductive paths extending through the dielectric substrate, the electrical connection being through direct electrical contact, indirect electrical contact through another conductor, or capacitive coupling, wherein the processing unit and the sensor electrodes are electrically connected via at least the first plurality of conductive paths and the second plurality of conductive paths, and   wherein the processing unit is configured to detect a signal at each of the sensor electrodes.   
     
     
         17 . The fingerprint sensor assembly of  claim 16 , further comprising:
 conductive coupling points disposed at an interface between the circuit board and the processing unit, wherein each of the second plurality of conductive paths terminates at one of the conductive coupling points, wherein the second plurality of conductive paths are electrically connected to the processing unit through the conductive coupling points.   
     
     
         18 . The fingerprint sensor assembly of  claim 17 , wherein the circuit board is encapsulated in a polymer resin that is stiff when cured.