Electrochemical deposition of hard magnetic materials for MEMS applications

In this dissertation, electrochemical deposition techniques of cobalt-based hard magnetic alloys and magnetic particle-ferromagnetic matrix composites are investigated in detail. Two cobalt alloy electrodeposition techniques have been developed to deposit thick (>10mum) hard magnetic films for MEMS applications. Residual stress induced by electrodeposition in these materials has been predicted and reduced based on the experimental results. The concept of magnetic composite electrodeposition (MCE) is proposed and its feasibility has been confirmed by experimental results. The MCE technique is further optimized by using a BaFe12O19-CoNiP system based on a systemic investigation of a variety of processing factors, which can affect the magnetic particle incorporation fraction. Using this optimized technique, micro-arrays with various shapes have been realized with a minimum feature size of 8mum. These micro-arrays exhibit excellent hard magnetic properties which are particularly well suited for use as magnetic MEMS actuator components.