Research on Microelectromagnetic Relays

A new microelectromagnetic relay is presented and fabricated based on micromachining technology, aiming at the miniaturization and high manufacturing efficiency of electromagnetic relays. This microrelay is composed of a lower magnetic circuit, a planar exciting coil, and an upper magnetic armature. A complete magnetic circuit is composed, and the “ON” and “OFF” states are controlled by the current of the exciting coil. The dimension of this microrelay is 5 mm × 5 mm × 0.4–mm. The fabrication process mainly includes lithography, sputtering, electroplating, etching, sacrifice-layer technology, etc. Electromagnetic force is calculated theoretically. The calculation results are used for the optimization design of the armature and the number of turns of the exciting coil. A microelectromagnetic relay is fabricated and the initial test results are given. The resistance of the exciting coil is about 300 Ω. The switch-on state resistance is about 1.7 Ω at an exciting current of about 50–mA. Translated from Journal of Beijing University of Technology, 2004, 30(2) (in Chinese)