Application of polyimide to bending-mode microactuators with Ni/Fe and Fe/Pt magnet

Out-of-plane polyimide (PI) electromagnetic microactuators with different geometries are designed, fabricated and tested. Fabrication of the electromagnetic microactuators consists of 10 μm thick Ni/Fe (80/20) permalloy deposition on PI diaphragm by electroplating process, electroplating of copper planar coil with 10 μm thick, bulk micromachining, and excimer laser selective ablation. They are fabricated by a novel concept to avoid the etching selectivity and residual stress problems during wafer etching. A simulation model is created by ANSYS software to analyze the microactuators. The external magnetic field intensity (Hext) generated by the planar coil is simulated by this software. Besides, to provide bi-directional and large deflection angles of the microactuators, hard magnet Fe/Pt is deposited at low temperature of 300 °C by sputtering onto the PI diaphragm to produce a perpendicular magnetic anisotropic field. This magnetic field can enhance the interaction with Hext to induce attractive and repulsive bi-directional force to provide a larger displacement. The results of the magnetic microactuators with and without hard magnetic are compared and discussed, respectively. The preliminary result reveals that the electromagnetic microactuators with hard magnet exhibit a greater deflection angle than that without one.