Stacked piezo ceramics are also named PZT stacks, are kind of piezo components which are composed ceramic thin pieces with many ceramic layers and internal electrodes. By comparison with london crystals with single-layer, they possess various features including small scale, low voltage, high power, low heating consumption, large deformation and force, and very high displacement resolution, which is able to realize Nano-level control accuracy.
There are many metal bonding methods such as fusion bonding, pressure welding, brazing, etc. Piezo elements welding generally uses braze welding way. By heating solder with low melting point, make it flow and infiltrate into area between wire and piezo elements, and they are connected together after solidify. In general, bond wires on both positive and negative electrodes of piezo components, or separately bond on metal sheets and piezos. According to different requirements for large quantity and standardized piezo crystals, it can also be divided into manual bonding and automated welding by equipment.
When some crystals are deformed by the application of an external stress, their crystalline structure is such that charge separation between the positive and negative ions establishes an polarization phenomeno, and the equal electrical charges appear across its two opposite faces. When the force is removed, it will return to the uncharged state. This phenomenon is called piezoelectric effect, also referred to direct piezoelectric effect. In addition, the polarity of the charge also changes along with the direction of the force, the amount of charge is proportional to the applied force value.
Piezo ceramic is the special ceramic material due to its piezoelectric property. Once affected by a external force, piezo material has ability to convert the mechanical energy into electrical energy, and vice versa, it can convert the electrical energy into mechanical energy on condition that the alternating voltage is applied across the piezoelectric ceramics.