Capacitive touch sensor

An apparatus, comprising:

• a circuit board having a first conductive sensor pad on a circuit board surface;
• a conductive overlay having:
• a first overlay surface;
• a second overlay surface opposite the first overlay surface such that the conductive overlay has a first thickness between the first overlay surface and the second overlay surface;
• a protrusion protruding from the second overlay surface and having a protrusion surface that is flat and parallel to the second overlay surface, the protrusion having a second thickness between the first overlay surface and the protrusion surface that is greater than the first thickness, wherein the protrusion is configured to act as a second conductive sensor pad;
• and
• a touch portion that includes a portion of the second overlay surface and the protrusion, wherein the protrusion is substantially centered in the touch portion and wherein the touch portion is configured to deflect in response to a touch on the first overlay surface at the touch portion;
• and
• a spacer protruding from the second overlay surface at a position outside of the touch portion and having a third thickness chosen such that the spacer is configured to reduce deflection of the conductive overlay at the position outside of the touch portion in response to a touch on the first overlay surface at the touch portion,
• wherein the circuit board, the conductive overlay, and the protrusion are arranged such that:
• the second overlay surface faces the circuit board surface,
• the second overlay surface and the first conductive sensor pad are separated by a first distance such that the second thickness causes the protrusion surface and the first conductive sensor pad to be separated by a second distance, and
• the protrusion surface and the first conductive sensor pad have an overlapping area.

An apparatus comprising:

• a circuit board;
• a first capacitor plate disposed on the circuit board;
• a set of spacers disposed on the circuit board alongside the first capacitor plate;
• and
• a conductive overlay disposed on the set of spacers, wherein the conductive overlay includes:
• an exterior surface disposed away from the first capacitor plate;
• a first interior surface disposed towards first capacitor plate, wherein:
• the conductive overlay has a first thickness between the exterior surface and the first interior surface;
• and
• the first interior surface is separated from the first capacitor plate by a first distance in an untouched configuration;
• and
• a second interior surface disposed towards the first capacitor plate, wherein:
• the conductive overlay has a second thickness between the exterior surface and the second interior surface that is greater than the first thickness;
• the second interior surface is separated from the first capacitor plate by a second distance in the untouched configuration;
• and
• the second distance is less than the first distance.