External Electrode/Termination

An external electrode or termination is a critical component in piezoelectric stacks that serves as the electrical interface between the piezoelectric ceramic layers and external circuitry. It facilitates the application of voltage to induce mechanical displacement (actuation) or the collection of electrical charge from mechanical stress (sensing). These terminations are designed to ensure reliable electrical contact, minimize signal loss, and withstand mechanical and thermal stresses during operation. They are typically applied to the outer surfaces of the stack and may include features for soldering, wire bonding, or connector attachment.

The external electrode/termination works by providing a conductive path for electrical signals to and from the piezoelectric ceramic layers. When voltage is applied through the termination, it creates an electric field across the piezoelectric material, causing deformation (inverse piezoelectric effect). Conversely, mechanical stress on the stack generates an electrical charge collected via the termination (direct piezoelectric effect). The termination must maintain low electrical resistance and good adhesion to prevent arcing, delamination, or signal degradation.