Electronic device having a biometric input system including a composite cover element
A biometric input system for an electronic device is provided. The biometric input system may be a fingerprint sensing system. The biometric input system includes a biometric sensing component, which may be a capacitive sensing component. The biometric input system also includes a composite cover element, which may be a dielectric cap or coating, and the biometric sensing component is capable of receiving a biometric input from a user through the composite cover element. Electronic devices including the biometric input system are also provided.
1 . An electronic device comprising:
an enclosure comprising a housing and a cover coupled to the housing;
a display positioned within the enclosure and below the cover; and
a biometric button assembly, at least a portion of the biometric button assembly positioned within an opening in the housing and the biometric button assembly comprising:
a biometric sensing component comprising an array of sensing elements configured to sense a fingerprint in response to a user press input;
an electrical connector electrically coupled to the biometric sensing component;
a circuit layer configured to process signals received from the biometric sensing component via the electrical connector; and
a dielectric composite material defining an input surface for the biometric button assembly and a thickness over an outward-facing surface of the biometric sensing component that is in a range from 90 micrometers to 200 micrometers, the dielectric composite material comprising:
a thermoset polymer material; and
oxide particles dispersed in the thermoset polymer material.
2 . The electronic device of claim 1 , wherein:
the electrical connector is bonded to the outward-facing surface of the biometric sensing component; and
the dielectric composite material at least partially encapsulates the electrical connector and the outward-facing surface of the circuit layer.
3 . The electronic device of claim 2 , wherein:
an exterior surface of the housing defines a recessed portion; and
the recessed portion defines a perimeter of the opening.
4 . The electronic device of claim 2 , wherein the oxide particles comprise silica particles having a size less than one micrometer.
5 . The electronic device of claim 4 , wherein:
the dielectric composite material further comprises pigment particles; and
the dielectric composite material includes from 5% to 20% by weight of the thermoset polymer material.
6 . The electronic device of claim 1 , the biometric button assembly further comprises a force sensor configured to detect a force applied to the input surface.
7 . The electronic device of claim 1 , wherein a dielectric constant of the dielectric composite material is in a range from 3 to 10.
8 . An electronic device comprising:
an enclosure defining an opening;
a display positioned within the enclosure; and
a bio-authentication button assembly defining an input surface, positioned at least partially within the opening in the enclosure, and comprising:
a biometric sensing component comprising a sensing layer;
a dielectric coating comprising 80% to 90% by weight of oxide particles and a thermoset binder material, the dielectric coating defining:
the input surface of the bio-authentication button assembly; and
a thickness that is greater than 5 micrometers and less than or equal to 200 micrometers over an outward-facing surface of the sensing layer; and
a processor positioned within the enclosure, operatively coupled to the biometric sensing component, and configured to authenticate a user based on an output of the biometric sensing component.
9 . The electronic device of claim 8 , wherein:
the dielectric coating is provided over a side surface of the sensing layer and defines a portion of a side surface of the bio-authentication button assembly; and
the input surface and the portion of the side surface of the bio-authentication button assembly protrude from the opening.
10 . The electronic device of claim 9 , wherein:
the dielectric coating defines a curved transition between the input surface and the portion of the side surface of the bio-authentication button assembly.
11 . The electronic device of claim 10 , wherein:
the input surface defines an elongated shape; and
the side surface is perpendicular to the input surface.
12 . The electronic device of claim 10 , wherein the oxide particles have a mean particle size less than one micrometer.
13 . The electronic device of claim 10 , wherein the bio-authentication button assembly further comprises:
a carrier structure configured to translate in response to a user press input; and
a switch assembly configured to detect a translation of the carrier structure in response to the user press input.
14 . The electronic device of claim 8 , wherein the bio-authentication button assembly further comprises:
a circuit layer conductively coupled to the biometric sensing component; and
an interior package layer formed of a molding compound different from the dielectric coating and at least partially encapsulating the circuit layer.
15 . An electronic device comprising:
a housing defining an opening along a side surface of the electronic device;
a touch-sensitive biometric button assembly extending partially through the opening and comprising:
a biometric sensing component including a sensing layer; and
an exterior package layer defining a cap for the touch-sensitive biometric button assembly, disposed over the sensing layer, and formed from a dielectric material comprising:
oxide particles having a mean particle size less than 1 micrometer; and
a thermoset polymer material; and
a display positioned at least partially within the housing.
16 . The electronic device of claim 15 , wherein:
the dielectric material encapsulates an outward-facing surface and a side surface of the biometric sensing component; and
the electronic device further comprises a circuit layer that is conductively coupled to the biometric sensing component.
17 . The electronic device of claim 16 , wherein the dielectric material defines a thickness greater than 5 micrometers and less than or equal to 200 micrometers over the outward-facing surface of the biometric sensing component.
18 . The electronic device of claim 17 , wherein:
a wire bond conductively couples an outer surface of the biometric sensing component to the circuit layer; and
the dielectric material at least partially encapsulates the wire bond.
19 . The electronic device of claim 17 , wherein the sensing layer includes an array of field sensing elements.
20 . The electronic device of claim 15 , wherein the mean particle size of the oxide particles is greater than or equal to 50 nm and less than or equal to 500 nm.