PI (Physik Instrumente) published a white paper on the development and test of highly reliable multilayer piezo actuators. The white paper describes the development and lifetime tests of ceramic encapsulated actuators under different operating conditions (DC and AC). The actuators are compared to polymer coated piezo ceramic actuators in long term tests. Equations and graphs for lifetime calculation under different operational and environmental conditions and special internal electrode designs for stress reduction are discussed.
The white paper is titled, Development of Highly Reliable Piezo Multilayer Actuators and Lifetime Tests under DC and AC Operating Conditions.
Multilayer Piezo Actuators White Paper Abstract
Piezoelectric multilayer actuators are the driving force behind the most challenging nanopositioning applications. These types of actuators have been in use for about two decades and have reached maturity several years ago. Continuous improvements are based on long term tests and exact knowledge of the environmental operating conditions and failure modes allows to push the limits of this technology even further.
The paper presents the results of an extensive study involving up to four environmental chambers and more than 1,000 actuator samples to develop a grid of 13 humidity and temperature conditions. Weibull-analysis is used at every condition to determine the DC-voltage dependent lifetime of the cofired PICMA multilayer actuators. In addition to the (most critical for precision positioning applications) DC tests, behavior under large-signal AC-conditions with up to 1010 cycles for different functions as well as temperature-conditions was also evaluated. Three patented design features of the latest actuator generation are based on the findings.