High strength rare earth-iron-boron printed magnets used in a long throw-high force electromagnetic actuator with microfabricated coils

Rare earth-iron-boron magnets were successfully integrated in a surface micromachined electromagnetic actuator. The magnets are 2000 by 1000 μm with thickness varying from 100 to 200 μm and were screen printed on electroplated cantilever beams fabricated above 40 turn planer coils on a silicon wafer. The magnetic paste used to form the magnets was made from 40 μm diameter spherical powder with a polyimide binder. The residual induction (B_r) was 3000 Gauss (0.3 T) and the intrinsic coercivity (H_ci) was 8050 Oe (644 kA/ m). Displacements of more than 1000 μm with 200 mA of current and repulsive and attractive forces on the order of 1 μN/mA at were demonstrated. The magnets produced forces on the order of 3 mN when in contact with ferromagnetic metals (Fe) or similar magnets.