An electrostatic actuator driven small signal relay fabricated by silicon micromachining has been developed. Compared to electromagnetic relay motors an electrostatic actuator offers the advantage of extremely low driving power. The actuator consists of a variable capacitor with two electrodes - a first flat and fixed electrode on an insulating carrier chip and a second in form of a bent silicon leaf fixed at one edge to a silicon chip forming a "moving wedge" in between. Due to the driving voltage applied the electric field provides an attractive electrostatic force causing perfect relay switching. The actuator size is about 1.5 mm~2 and pull-in-voltages below 24 V are achieved. The switching characteristic has been analysed theoretically and experimentally showing a perfect switching hysteresis and contact forces in the range of 1 mN. Due to low movable masses no bouncing occurs during switching. The micro contacts fabricated by electroplating perform switching of high load currents. Electrical life time tests with more than 6 Mio. cycles at switching currents of 100 mA have been performed.
展开▼
