"Typical electrical-based fingerprint sensors today comprise a semiconductor body, or die, on which is formed an array of sensor elements and related circuitry. When packaged, the sensor elements are often exposed for contact with a user's finger, or through a protective material. Typically, the sensors operate according to principles that use distance between the sensor surface and a region of the user's finger to construct an image of the user's fingerprint. Accurate operation of such sensors can accommodate no more than a minimal gap between the sensor surface and the fingerprint to be sensed. Therefore, the sensor surface itself is most often left uncovered, and a user places a finger directly into contact therewith in the process of fingerprint sensing."
Apple notes that traditionally the bezel and the encapsulated die have been separate elements, brought together in assembly; rather than encapsulated together. This can lead to undesireably large devices. The company details a fingerprint sensor which comprises a substrate to which is mounted a die containing sensor circuitry and at least one conductive bezel.
By encasing both the bezel and the sensor die in the encapsulation structure, those elements may be brought closer together than heretofore possible. In addition, the encapsulation structure physically protects the bezel and sensor die, and in particular maintains the spacing therebetween, in a fashion not possible by currently known device designs.
Apple is rumored to be releasing an iPhone 5S this fall which will feature a fingerprint scanner based on its acquisition of Authentec.