The new actuators with copper electrodes are designed with a minimum proportion of inactive zones in the multilayer actuator and thus achieve the highest possible volume efficiency. As a result, the actuator performance is 20 percent higher than that of conventional designs of the same size. This improvement is owed to a new ceramic material developed by TDK, whose piezoelectric coupling – conversion of electrical power into mechanical power – is higher than 75 percent. Thanks to this material in combination with the volume efficient actuator design, these copper piezo actuators have a significantly higher performance than predecessor models and competitor products.
While competing piezo vendors actuator vendors use silver-palladium alloys for their internal electrodes, TDK claims to be the only company to the relatively inexpensive use copper. Despite the higher price, silver has its drawbacks: In the case of very high proportions of silver in the electrode material, silver migration can occur and cause failure of the actuators – especially under high humidity conditions. In addition to the use of copper internal electrodes, TDK has developed a new lead-free high melting metal bond that exhibits no loss of contacting, even at high temperatures. The new piezo actuators withstand a 2000-hour test at 200 °C with no signs of embrittlement.
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