Magnetically-actuated bending-mode microactuators with excimer laser ablation

Bending-mode polyimide-based (PI) electromagnetic microactuators with different geometries were fabricated and tested. Fabrication of the electromagnetic microactuator consists of electroplated 10 μ m thick Ni/Fe (80:20) permalloy on a PI diaphragm, high aspect ratio electroplating of a copper planar micro-coil, bulk micromachining, low-temperature bonding, and 248 nm excimer laser selective ablation. They were fabricated by a novel concept avoiding the etching selectivity and residual stress problems which occur during wafer etching. The magnetic field generated by the planar micro-coil was used to provide an external magnetic field (N-ext) to interact with Ni/Fe on the PI diaphragm, by which a repulsive force can be induced to provide a large deflection angle. The deflection angle of the microactuator with different H-ext values was measured. Preliminary results show that 82° can be obtained. In addition, to provide a high strength and low temperature bonding process for the microactuator system, a polymer-based photoresist with patternable characteristics was used as the adhesive bonding material. The bonding results for different photoresists are compared and discussed.