摘要：To meet stringent requirements in vacuum and cleanness for s.m.conductor manufacturing, a new power drive module for selective Compliant Ass.m.ly Robot Arm （sCARA） type robot has been developed for wafer-transfer. In order to obtain complete hermetic volume for higher vacuum and prevent leakage of hazardous gases, feedthrough motions involving transfer between the vacuum and motors are achieved by the use of metal bellows and magnetic coupling. An analysis of the coaxial-type magnetic coupling by employing the technique of current sheet model is presented. This approach is proved to be a precise and easy method. The construction of power drive module shows its advantage in maintaining ultrahigh vacuum and also enhances the efficiency for transporting the wafer, as compared with conventional design.