Micro-electro-mechanical system having movable element integrated into leadframe-based package

A microelectromechanical system (MEMS) device, comprising:

• a leadframe having a first surface, the leadframe defining a plurality of leads and a segment;
• a polymeric compound deposited over the leadframe first surface including at the leads and a peripheral portion of the segment, leaving the first surface at another portion of the segment unencapsulated at a bottom of an opening through the polymeric compound, the unencapsulated portion defining a movable part of the MEMS device;
• and
• a semiconductor chip having electronic circuitry on a first chip surface connected at the leads to a second surface of the leadframe, so that the first chip surface spans across the movable part, separated from the movable part by a gap.

A microelectromechanical system (MEMS) device, comprising:

• a leadframe having first and second surfaces, the leadframe defining a plurality of leads and a segment;
• a polymeric compound having a thickness, the polymeric compound encapsulating the second leadframe surface, leaving a portion of the second leadframe surface at the segment unencapsulated at an opening through the thickness;
• a foil suitable as a movable part of the MEMS device defined by a thinning of the segment at the location of the unencapsulated portion;
• and
• a semiconductor chip having electronic circuitry on a first chip surface connected to the leads at the first leadframe surface so that the first chip surface with the electronic circuitry faces and spans the foil, separated from the foil by a gap.