A new basic technology for magnetic micro-actuators

This paper presents a new technology for the fabrication of electromagnetic micro-actuators. This technology allows “U-core” electromagnets to be built on ferromagnetic substrates. The electromagnets consist of multi-level copper coils and electroplated NiFe poles. Combined with a NiFe “keeper”, an electromagnetic actuator is obtained, which can generate a magnetic force up to several tens of mN. The actuator can be implemented in several applications, such as valves, motors and relays. In this paper, an electromagnetic microrelay, to be used, for instance, in the automatic test equipment (ATE) market, is described. First experimental results of the relay, using a driving coil of 127 turns and having gold contacts, have shown an on-resistance of less than 0.4 Ω for an input (driving) current of 8 mA, corresponding to a driving power of 14 mW. These data compare favorably well with previous results of electromagnetic microrelays as presented in the literature