A new process to fabricate the electromagnetic stepping micromotor using LIGA process and surface sacrificial layer technology

In this paper, a new process to fabricate an electromagnetic stepping micro motor using surface sacrificial layer technology (SSLT) is illustrated, and the SEM photo of the stepping micromotor is showed. The torque of the step ping micromotor with maximum torque of 60 mu Nm is directly calculated by u sing electromagnetics laws and the law of conservation of energy. The stato r and the shaft and the rotor of the micromotor with the material of nickel are first all fabricated by normal LIGA process at the same time. The sacr ificial layer structure with the material of AZ resist is made on the surfa ce of the rotor by using SSLT. The stator and the shaft are fixed together with copper substrate instead of the old Ti substrate by electroplating. Af ter removing the Ti substrate, PMMA resist and the sacrificial layer struct ure, the rotor is separated from the stator and new copper substrate, and c an rotate on the new substrate driven by magnetic force. The four coils wit h 300 turns each are wound on iron bars by hand using microscope and steppi ng motor. The bars are assembled by hand into the stator holes from rear of new copper substrate to form a magnetic circuit with the stator and the ro tor. A power supply with four consecutive pulses provides the current for t he coils wound on the iron bars and produces the magnetic force to drive th e rotor to run with the speed of 60 rpm.