Last Updated on May 2, 2023 by You Ling
1、What are piezoelectric ceramic shear plates?
Piezoelectric ceramic shear plates utilize the shear effect of piezoelectric ceramics (d15), generating shear displacement by applying positive and negative voltages. They provide lateral displacement, and by stacking multiple shear plates using epoxy resin and copper foil, larger lateral displacements can be achieved. By combining shear stacks and z-axis motion of piezoelectric ceramics, multi-axis motion stacks such as XY, XZ, YZ, and XYZ can be formed.
2、Piezoelectric ceramic shear stacks
Piezoelectric ceramic shear stacks consist of multiple discrete piezoelectric ceramic shear plates bonded together with epoxy resin and copper foil. Individual stacks move along a single lateral axis by applying positive or negative bias voltage. Positioners providing displacement along two lateral axes join the top plate of one piezoelectric ceramic shear stack to the bottom plate of another. Three-axis positioners bond two shear stacks to a discrete longitudinally moving piezoelectric ceramic stack, with the latter providing displacement in a direction perpendicular to the surface of the stack (the longitudinally moving stack provides displacement only along the positive displacement axis and cannot have a reverse bias applied to it), and its driving voltage range is different from that of the piezoelectric ceramic shear stack. Two leads are connected to each stack for individual control, allowing for precise positioning of the positioner’s top surface.
Both electrodes of the shear plate are the same. The working direction is indicated by the cutting angle. According to the sign convention, when a positive voltage is applied to one electrode surface, this surface will generate a relative displacement towards the edge of the cutting angle. External electrode connections can be achieved through mechanical contact, welding, conductive adhesive bonding, or lead bonding. Mechanical connections can be made using a copper spring connected to the external electrode. The gold electrode on the shear plate provides excellent conductivity while preventing electrode oxidation. Each piezoelectric shear plate is made from a single layer of piezoelectric ceramic, with electrodes coated on the top and bottom to apply the driving voltage. Copper sheets and lead terminals are glued to the top and bottom of the piezoelectric ceramic chip, respectively. Applying a voltage lower than -200 V or higher than 200 V to the electrodes will shorten the life of these chips and may cause mechanical failure.
Single plate displacement of 1.5µm
Stacking for larger displacement or XYZ three-dimensional
The lateral displacement of the piezoelectric ceramic shear chip along the lateral axis is 1.3 µm, while that of the piezoelectric ceramic shear stack is 7.0 µm. Multi-axis positioners can achieve 7.0 µm of displacement on each axis.
The hysteresis caused by the shear strain of piezoelectric ceramics can reach up to 40%, which is significantly higher than the hysteresis caused by the axial strain of piezoelectric components (providing longitudinal displacement).
Optical Fiber Stretching
When an optical fiber is used as an optical delay line, the optical pulses passing through the fiber experience a delay. When the fiber is stretched, the induced strain causes changes in the fiber’s length, which in turn results in additional pulse delays. Optical fiber stretching mechanisms utilize the extension of piezoelectric ceramics to push the distance between external mechanical structures, while the contraction of piezoelectric ceramics causes the mechanical structures to rebound, thereby stretching the fiber wound around the external mechanical structures.
Piezoelectric Dispensing Valve
The piezoelectric jet dispensing valve is a non-contact jet dispensing valve. Piezoelectric ceramics serve as a key component of the piezoelectric jet dispensing valve, controlling the valve’s opening and closing through differential micro-motions. This system boasts excellent dispensing accuracy and process control. The non-contact dispensing method eliminates Z-axis movement, achieving higher production efficiency and avoiding needle collisions with workpieces, which in turn increases the yield rate. The core controller can drive a 10 μF load with a 50 μs step time.
This technology is widely used for the controlled flow and high-speed dispensing of various adhesives, including mounting adhesives, conductive silver pastes, IC packaging adhesives, underfill adhesives, sealing adhesives, and surface coating adhesives.
In-situ testing (micro-mechanical testing combined with visualization monitoring) involves conducting mechanical property tests on specimens at the nanoscale. This method is compatible with integrated scanning electron microscopes (SEMs), X-ray diffractometers (XRD), Raman spectrometers, atomic force microscopes (AFMs), image controllers (CCDs), and metallographic microscopes for full-process dynamic monitoring of microscopic deformation and damage in materials. In-situ testing provides in-depth insights into the microscopic mechanical behavior, damage mechanisms, and the correlation between load effects and material properties of various materials and their products.
Wing Vibration Damping
Piezoelectric bending plates dynamically adjust the geometric shape of wing sections, suppressing turbulence development and controlling dynamic stall to achieve aerodynamic gain in wing performance. This is an effective method of active flow control.
Optical Fiber Sensors
Optical fiber sensors transmit light from a light source through an optical fiber to a modulator, where the light interacts with the test parameter entering the modulation region, causing changes in the optical properties. Piezoelectric ceramics play a role in the interaction between light and electricity. By using the deformation of piezoelectric ceramics, the distance between optical fibers can be changed, altering the intensity, wavelength, and frequency of the light.
Precision positioning of solder material is crucial in ultrasonic welding. Piezoelectric clamps use electrical signals to control the elongation or contraction of piezoelectric ceramics, which in turn control the clamping and release of the clamp jaws, driving the movement of solder for precise welding.