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 (H
_ci
) and remanence (B
_r
) 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.