Fatigue testing machine of micro-sized specimens for MEMS applications

A new type of fatigue testing machine for micro-sized specimens for MEMS applications has been developed. This fatigue testing machine consists of a magnetostrictive actuator which is able to impart small displacements to a specimen upto 20 mum with resolution of 5 nm. The actuator is connected to a metal shaft and a diamond tip of 5 mum in radius is attached to the end of the shaft. Small displacements are applied to the specimen through the diamond tip. This makes it possible to construct a high stiffness loading fixture. The magnitude of load applied to the specimen is measured by a strain gauge type load cell with a load resolution of 10 muN. The specimen stage and load cell can be moved to adjust the loading position precisely by a stepping motor at a translation resolution of 0.1 mum. Cantilever beam type specimens with dimensions of 10 x 12 x 50 mum(3) were prepared from a Ni-P amorphous thin film by focused ion beam machining. Very small cyclic load (DeltaP = 0.1 - 40 mN) was able to be applied to the specimen successfully. This machine appears to be promising for evaluation of fatigue properties for micro-sized specimens for MEMS applications.