Cantilever test stand

Cantilever test stand

The picture on the left shows a vacuum high-throughput test stand for the characterization of the actuator response of thin film SMA (including hot/cold plate, liquid nitrogen (LN2) and electrical feeds). Stress change measurements can be conducted in this high vacuum system equipped with a heating/cooling plate (HCP604SCV, Instec Inc., 4”x 4”, -100 °C up to 600 °C, temperature stability ± 0.2 °C, temperature uniformity ± 0.2 °C/inch). Water condensation at low temperatures or oxidation at elevated temperatures is prevented by the vacuum. The change of the temperature-dependent film stress (Δσ) at heating/cooling rates of typically 5 K/min is monitored by the deflection of each cantilever, as detected by a laser beam (parallel line optics) reflected at the free ends onto a screen and recorded by a camera. The stress can be calculated by the well known Stoney-Equation.

The test stand is a powerful tool to determine the reversible phase transformation behavior of thin films under substrate-induced stress.