Wax-bonded NdFeB micromagnets for microelectromechanical systems applications

A microfabrication technique is reported for the fabrication of wax-bonded micromagnets in the 100μm–1mm range. This dimensional size is not typically achievable by thin-film deposition techniques or by conventional macroscale magnet processing, and is of interest for magnetic microelectromechanical systems applications. The magnet fabrication approach incorporates a wax powder binder to “lock” the magnetic microparticles together to improve the coercivity. In practice, a NbFeB powder and wax powder are packed into pre-etched trenches in a silicon wafer and subsequently heated, allowing the wax to melt and bond the magnetic powder. Using this method, 500×500×320μm3 magnets have been demonstrated with a coercivity of 737kA∕m and a maximum energy product of 16.6kJ∕m3.