Multilayer Piezo Actuator Stacks

High active stacks with copper inner electrodes

Numerous high-end solutions use piezo actuators with High Active Stack (HAS) technology from TDK, for example in nano-positioning, valve controls for liquids and gasses in process engineering, and in semiconductor manufacturing. Based on copper inner electrodes in multilayer piezo actuators – this patented technology by TDK has been used in fuel injection systems in automotive for over 20 years.

High active stacks offer superior performance, robustness to moisture, and a longer lifetime, even in harsh conditions, compared to conventional silver-palladium (AgPd) stacks.

What’s special in TDK’s actuator stacks?

Minimized inactive areas for higher performance and longer lifetime

The inactive areas in an actuator are a cause of mechanical stress during operation. The larger the inactive areas are, the more mechanical stress the actuator will have, creating larger cracks in the ceramic. The width of the inactive area per layer in TDK stacks is 100 µm (compared to 400 µm in conventional ones) which significantly reduces mechanical stress, enables longer lifetimes and higher operating voltages (of up to 180 V), generating a higher stroke or elongation (ca. +20 %), hence the name High Active Stacks.

Copper inner electrodes for superior robustness against humidity and cost-effectiveness

Conventional stack actuators use silver-palladium alloy for the inner electrodes. Silver is a very ductile metal under humid conditions and electric fields. As a result of this phenomenon, short circuits or failures occur between the actuator's inner electrode layers. TDK HAS components use copper in their inner electrodes to prevent migration between their layers. Additionally, copper prices are more stable than palladium, enabling cost-effective solutions with superior performance. Win-Win!

A lead-free high melting metal bond for operation at high temperatures

The metal bonds that connect the external electrodes are also exposed to high mechanical stress during operation, especially at high temperatures. TDK developed a new lead-free high-melting metal bond that does not become brittle even at high temperatures and thus does not lose contact. This innovative bond is more reliable than a lead-based solder for electrode contacting as its properties are more porous and flexible. TDK HAS devices passed a 2000-hour test at 200 °C with no signs of embrittlement; conventional solder contacts failed after 1500 hours at temperatures of only 180 °C.

Portfolio overview


	COM10S5	COM30S5	COM45S5	COM30S7	COM27S3
Dimensions [mm] (l x w x h)	5.2 x 5.2 x 10 Passivated	5.2 x 5.2 x 30 Passivated	5.2 x 5.2 x 45 Passivated	7.0 x 7.0 x 30 Passivated	3.4 x 3.4 x 27 Leaded
Preload [N]	730	730	730	1320	320
Stroke [µm]	16	55	83	55	47
Capacitance [µF]	1.0	3.4	5.3	6.3	1.3
Stiffness [N/µm]	79	25	16	50	12
Blocking force [N]	1400	1400	1400	2600	600

Applications

Countless high-end solutions in nano-positioning technology, micro-dispensing valves for semiconductor manufacturing and adhesives in production processes, and bonding wire machines are based on piezo actuators from TDK.

Benchmark

TDK’s HAS technology impresses with its outstanding blocking force and stroke compared to conventional silver-palladium stacks.

Scatterplot of force [N] vs stroke [µm] of piezo stack 7 x 7 x 30 mm³ @ 160 V

Elevated temperature test
Weibull – 95 % CI

Dynamic humidity test
Weibull – 95 % CI

Get data sheets and search

Type	Dimensions (l x w x h) (mm)	Stroke (µm) at 160 V	Stiffness (N/µm) (typ.) at 160 V _(kstack)	Blocking force (N)	Ordering code
COM10S5	5.2 x 5.2 x 10	16 ±10%	79	1400	Z63000Z2910Z001Z78
COM27S3	3.4 x 3.4 x 27	47 ±10%	12	600	Z63000Z2910Z001Z77
COM30S5	5.2 x 5.2 x 30	55 ±10%	25	1400	B58004M4030A020
COM30S7	7.0 x 7.0 x 30	55 ±10%	50	2600	Z63000Z2910Z001Z70
COM45S5	5.2 x 5.2 x 45	83 ±10%	16	1400	B58004M4040A020

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