Integration of Thick-Film Permanent Magnets for MEMS Applications

This paper presents a method of integrating thick permanent magnetic films into a microfabrication process. An enhanced binding method consisting of a hybrid of Parylene N and Parylene C thin films was used in conjunction with various types of NdFeB powders to create embedded permanent magnet films. A systematic study of composite magnetic powders was developed using three different powders in order to control intrinsic coercivities (Hci) and remanence (Br) properties. In addition, four types of dispensing methods were investigated. A liquid dispensing method demonstrated the highest fill factor (79%) for a 400-μm-thick film with an enhanced remanence value of 0.59 T. A range of remanence values from 0.2 to 0.59 T were developed by varying the concentration of multiple magnetic powders within the composite material. Validation of the integrated magnetic material into a microelectromechanical system device was demonstrated through a polymer on a silicon cantilever structure.