Force measurements on U-shaped electrothermal microactuators: applications to packaging

摘要

The current paper critically reviews the prospects for the electrothermal actuation of elastic fixtures used as packaging elements for opto-electronic components. A convenient design methodology is presented together with a practical scheme for both prototyping out-of-plane bimorph actuators and measuring the vertical forces that they can deliver. A test bench has been assembled capable of measuring both the displacement and the restoring force delivered by such actuators which are patterned using laser micromachining of a bilayer consisting of 500 nm titanium tungsten (Ti-W) and 3 µm silicon nitride (SiN) thin films on a silicon substrate. An analytical model is derived to predict the dependence of the restoring force on the input electrical power and topology of the actuator. Experimental results are presented for bilayer actuators made of Ti-W/SiN in which attainable forces are of the order of 25 µN for input powers of 70 mW. An approximate theoretical model correlates well on the measured results of restoring force for different actuator geometries and supply currents. A packaging prototype was successfully tested using 550 µm long U-shape actuators with a gap width of 200 µm. These were able to move macroscopic components with rotations of up to 3° . [PUBLICATION ABSTRACT]