Development of two-stage solidification technology for implementing micro structures with liquid magnetic polymer and solid magnetic anisotropic polymer

Abstract

This study presents two-stage solidification technology for fabricating micromagnetic polymer composite (MPC, polymer with magnetic particles) structures. In this process, ultra-violet (UV)-light polymer curing is used for the first stage of MPC solidification. The surface of the MPC structure is solidified in this step. Moreover, thermal polymer curing is employed for the second stage of MPC solidification. The second stage of curing was mainly for the body solidification of the MPC. The distribution of magnetic particles in MPC can be specified by applying a magnetic field during the second solidification process. Based on the presented process technologies, microstructures with liquid MPC (NdFeB particles of different wt% in liquid polymer), isotropic solid MPC and anisotropic solid MPC have been demonstrated. Microdevices with liquid MPC embedded in solid micro balls and thin layers are also demonstrated. Various tests are performed to characterize the magnetic properties of the fabricated micro MPC structures. Measurements show that the fabricated solid MPC has reasonable coercivity, as compared with bulk materials. However, the remanence and the saturation magnetization still need to be improved.