Influence of Permanent Magnetic Properties on Magnetic Pattern Transfer for Magnetic MEMS

Generating a high magnetic flux density from a thin-film or thick-film permanent magnet is essential for the high performance of magnetic MEMS devices, such as microsensors and microactuators. When thick-film magnets with a low aspect ratio are used in the devices, it is necessary to reduce the generation of reverse magnetic fields in the magnet, and alternating multi-pole magnetization with a narrow pitch is effective. We have developed a batch method for transferring a narrow-pitch alternating multi-pole magnetic pattern from a master magnet to other magnets. In this method, the magnetic pattern of the master magnet, which can maintain its coercivity at high temperatures, is transferred to a magnet whose coercivity decreases at high temperatures. The experimental results show that a high intrinsic coercivity and a high residual flux density unaffected by irreversible demagnetization are necessary to obtain a high transfer ratio and surface magnetic flux density for the magnet to which the magnetic pattern is transferred.